Important Questions

Balbharti Maharashtra State Board Class 11 Geography Important Questions Chapter 8 Biomes Important Questions and Answers.

Maharashtra State Board 11th Geography Important Questions Chapter 8 Biomes

Complete the chain.

Question 1.

A	B	C
(1) Tropical Rainforest	(1) 10° to 20° N and S	(1) Khejari, acacia, century plant, cactus
(2) Tropical Deciduous	(2) 20° to 30° N and S	(2) Elephant grass, few shrubs, trees
(3) Savannah Grassland	(3) 0° to 10° N and S	(3) Teak, sal, sandalwood, bamboos
(4) Tropical Desert	(4) 5° to 30° N and S	(4) Mahogany, ebony, rosewood

Answer:

A	B	C
(1) Tropical Rainforest	(1) 0° to 10° N and S	(1) Mahogany, ebony, rosewood
(2) Tropical Deciduous	(2) 5° to 30° N and S	(2) Teak, sal, sandalwood, bamboos
(3) Savannah Grassland	(3) 10° to 20° N and S	(3) Elephant grass, few shrubs, trees
(4) Tropical Desert	(4) 20° to 30s N and S	(4) Khejari, acacia, century plant, cactus

Question 2.

A	B	C
(1) the Mediterranean	(1) 40° to 50° N and S	(1) Maple, elm, walnut, deodar
(2) Temperate Deciduous	(2) 40° to 55° N and S	(2) Willow, alder, poplar, various species of grasses
(3) Temperate Grassland	(3) 30° to 40° N and S	(3) Pine, oak, cedar, rosemary

Answer:

A	B	C
(1) Mediterranean	(1) 30° to 40° N and S	(1) Pine, oak, cedar, rosemary
(2) Temperate Deciduous	(2) 40° to 50° N and S	(2) Maple, elm, walnut, deodar
(3) Temperate Grassland	(3) 40° to 55° N and S	(3) Willow, elder, poplar, various species of grasses

Choose the correct option by identifying the correct correlation in the sentences.

Question 1.
Teak is the main tree in …………….. Biome.
(a) Tropical Rainforest
(b) Tropical Deciduous
(c) Savannah Grassland
(d) Tropical Desert
Answer:
(b) Tropical Deciduous

Question 2.
The ………………. Biome was known as ‘The Heaven for Hunting’.
(a) Savannah Grassland
(b) Tropical Desert
(c) Mediterranean
(d) Tropical Deciduous
Answer:
(a) Savannah Grassland

Question 3.
The ………………… Biome has been ideal for the development of cinema industry.
(a) Temperate Deciduous
(b) Temperate Grassland
(c) Taiga
(c) Mediterranean
Answer:
(c) Mediterranean

Question 4.
One type of tree species is the characteristic of ……………….. Biome.
(a) Taiga
(b) Tundra
(c) Mountain
(d) Tropical Rainforest
Answer:
(a) Taiga

Question 5.
The ……………… Biome is the coldest of the Biomes.
(a) Mediterranean
(b) Temperate Deciduous
(c) Temperate Grasslands
(d) Tundra
Answer:
(d) Tundra

Question 6.
In the grassland areas of Africa, ………………..
(a) various tribal communities inhabit
(b) Masais live along with their cattle
(c) Bedouin tribe lives by trade
(d) human life has flourished very well
Answer:
(b) Masais live along with their cattle

Question 7.
The Sherpas, Bakarwals, Lepchas, Bhutiyas, etc., are communities living in the …………………. mountain biome.
(a) Rockies
(b) Himalayan
(c) Alps
(d) Andes
Answer:
(b) Himalayan

Question 8.
The layer of the marine biome where the animals are adapted to survive on detritus under even greater pressure is ………………..
(a) the darkest and deepest layer
(b) the Euphotic layer
(c) the Disphotic layer
(d) the Aphotic layer
Answer:
(a) the darkest and deepest layer

Question 9.
The various species of grass that include purple needle grass, blue grama, buffalo grass, and galleta are found in ………………….
(a) Savannah Grassland Biome
(b) Temperate Grasslands Biome
(c) Tundra Biome
(d) Highland Biome
Answer:
(b) Temperate Grasslands Biome

Identify the correct correlation.

A : Assertion
R : Reasoning

Question 1.
A – The climate includes conditions like rainfall, temperature, humidity, soil conditions etc.
R – The boundaries of different biomes land are determined mainly by climate.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
Both A and R are correct and R is the correct explanation of A.

Question 2.
A – Different biomes have different animals and plants on the same trophic levels.
R – There can be many ecosystems within a biome.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(d) Both A and R are correct but R is not the correct explanation of A.

Question 3.
A – There is degradation in the biome of tropical rainforest biome.
R – There is increasing industrialization and agriculture in the biome of tropical rainforest.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(c) Both A and R are correct and R is the correct explanation of A.

Question 4.
A – The elephant grass grows in Savanah Grassland biome.
R – There are many grass eating animals therefore carnivores are large in number in Savannah Grassland biome.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(c) Both A and R are correct and R is the correct explanation of A.

Question 5.
A – The animals in tropical desert region are small and tend to burrow.
R – There are mainly herbivores in tropical desert region.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(a) Only A is correct.

Question 6.
A – In the aquatic biome top layer is called aphotic layer.
R – In the aquatic biome the middle layer is called disphotic layer.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(b) Only R is correct.

Question 7.
A – The subdivision of aquatic biome is based on salt content of water and the aquatic plants live there.
R – In marine biome there are three layers in water.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(d) Both A and R are correct but R is not the correct explanation of A.

Question 8.
A – Tourism has developed in mountain or highland biome.
R – People come here for paragliding, trekking and to get relief from heat.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(c) Both A and R are correct and R is the correct explanation of A.

Question 9.
A – Tundra is the coldest of the biome.
R – Animal life is very scarce here.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(c) Both A and R are correct and R is the correct explanation of A.

Question 10.
A – Many fruits and flowers are grown in the Mediterranean region.
R – Many heavy industries are developed in the Mediterranean region.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(a) Only A is correct.

Identify the incorrect factor.

Question 1.
The abiotic factors are-
(a) Soil
(b) Bacteria
(c) Water
(d) Sunlight
Answer:
(b) Bacteria

Question 2.
Herbivores found in the Tundra biome are-
(a) Reindeer
(b) Caribou
(c) Bears
(d) Wild horse
Answer:
(d) Wild horse

Question 3.
Tropical rainforest biome is in-
(a) Congo basin
(b) Amazon basin
(c) Andaman and Nicobar Islands
(d) Thailand
Answer:
(d) Thailand

Question 4.
Following birds are observed in the tropical desert biome-
(a) Vulture
(b) Bustard
(c) Barn owls
(d) Desert eagle owls
Answer:
(a) Vulture

Question 5.
The abiotic factors in an ecosystem include …………………
(a) air
(b) sunlight
(c) temperature
(d) animals
Answer:
(d) animals

Question 6.
The climatic conditions that determine the boundaries of different biomes on the land are ……………….
(a) rainfall
(b) temperature
(c) humidity
(d) relief
Answer:
(d) relief

Identify the correct correlations.

Question 1.

Tribes	Locations
(i) Pygmies	(a) Grassland areas of Africa
(ii) Masais	(b) Andaman and Nicobar Islands
(iii) Sentinels	(c) Himalayan Mountain biome
(iv) Sherpa	(d) Congo
	(e) Alaska

Answer:

Tribes	Locations
(i) Pygmies	(d) Congo
(ii) Masais	(a) Grassland areas of Africa
(iii) Sentinels	(b) Andaman and Nicobar Islands
(iv) Sherpa	(c) Himalayan Mountain biome

Question 2.

Trees	Biomes
(i) Ebony	(a) Tropical Deciduous
(ii) Sandalwood	(b) Tropical Desert
(iii) Khejari	(c) Tropical Rain forest
(iv) Willow	(d) Tropical Desert
	(e) Temperate Deciduous

Answer:

Trees	Biomes
(i) Ebony	(c) Tropical Rain forest
(ii) Sandalwood	(a) Tropical Deciduous
(iii) Khejari	(b) Tropical Desert
(iv) Willow	(e) Temperate Deciduous

Question 3.

Birds	Locations
(i) Pale crag martin	(a) Savannah Grassland Biome
(ii) Ostriches	(b) Temperate Deciduous Biome
(iii) Peregrine	(c) Tundra Biome
(iv) Ptarmigan	(d) Tropical Deciduous Biome
	(e) Tropical Desert Biome

Answer:

Birds	Locations
(i) Pale crag martin	(e) Tropical Desert Biome
(ii) Ostriches	(a) Savannah Grassland Biome
(iii) Peregrine	(b) Temperate Deciduous Biome
(iv) Ptarmigan	(c) Tundra Biome

Arrange the given statements as per given instructions.

Question 1.
Arrange the following Marine Biomes from the lowest to the uppermost level.
(a) Aphotic layer
(b) Darkest layer
(c) Euphotic layer
(d) Disphotic layer
Answer:
(c). (d), (a), (b)

Give geographical reasons.

Question 1.
Human life is not very easy in the Tropical Rainforest biome.
Answer:
Human life is not very easy in the tropical rainforest biome because-

1. Tropical Rainforest is present between 0° to 10° N and S.
2. There is no dry season – all months have an average precipitation of at least 60 cm.
3. The ground is marshy and covered with thick undergrowth.
4. The forest is very dense and impenetrable and inaccessible.
5. The rivers are infested with crocodiles, snakes and insects like mosquitoes and flies.
6. The conditions in the Tropical Rainforest are not favourable for human habitation. The indigenous humans in these parts are still in their primitive stage. They are engaged in primary occupations, such as gathering forest products, hunting, etc.

Question 2.
There is a degradation in the Tropical Rainforest biome.
Answer:

1. There is an increase in agriculture and industrialisation in this biome. Therefore, deforestation is on a large scale.
2. The biodiversity found in this biome is getting destroyed.
3. Golden lion tamarin, gorilla, orangutan, harpy – eagle, chimpanzee, poison dart frogs are threatened.
   Hence, there is a degradation in the tropical rainforest biome.

Question 3.
In Tropical and Sub-Tropical biomes, a large diversity exists in fauna.
Answer:

1. The biodiversity found in Tropical and Sub-Tropical biomes ranks second in the world,
2. In tropical region trees have a three-tier system, therefore every bird and animal have its own niche in the areas from the ground to the top of the tree.
3. Therefore, from microscopic organisms to large elephants, hippopotamus, rhinos, tiger, lion, gaur, monkeys, reptiles, etc., are found in huge numbers.
4. Birds like greater coucal, hornbills, Asian koel, peacock, vultures, falcon, pigeons, sparrows, etc., are found here.
5. Similarly, ants, butterflies, insects and worms are also found in plenty.
6. In grassland region, grass eating animals are more, therefore carnivores who are dependent on them are also high.
7. Thus, in Tropical and suh-tropical biomes, a large diversity exists in fauna.

Question 4.
The forests in Tropical Deciduous biomes are in danger.
Answer:

1. There is large scale deforestation and also wildfires.
2. Extensive use of fertilizers by humans and spray of insecticides has threatened many wild species.
3. Due to increasing population there is encroachment on forest areas for human settlements. Hence, the forests in Tropical Deciduous biomes are in danger.
4. The Temperate Grasslands biome is getting degraded.
5. The extent of commercial agriculture is increasing in this biome.
6. Industries are also increasing.
7. Meadows and pastures are reducing because of overgrazing.
8. Hence, the Temperate Grasslands biome is being degraded.
9. Life of Eskimos has changed In the Tundra biome.
10. In the Tundra biome, human settlements are very sparse.
11. Lapps, Samoyeds and Eskimos live in adverse climate.
12. Life of Eskimos has changed after they have come in contact with westernizers.
13. As they have started getting advanced instruments, their life and fishing methods have changed.
14. Thus, they have started exploitation of fish with the help of modern methods at a higher speed in this biome.
15. This biome is seeing development due to increased transportation and means of communication.
16. The standard of life has improved and this has affected the protected factors of this biome.

Differentiate between

Question 1.
Vegetation in Tundra and Mountain Biome.
Answer:

Vegetation in the Tundra Biome	Vegetation in the Mountain Biome
(i) The tundra is the coldest of the biomes.	(i) The temperatures are low and it decreases with increase in height.
(ii) The ground is frozen for 8 months of the year. There is a layer of permanently frozen ground below the surface, called permafrost.	(ii) Climate depends on altitude, location on leeward or windward side, orographic rainfall and snowfall on upper slopes of mountains.
(iii) Vegetation has adapted to the cold and the short growing season.	(iii) The vegetation has range from deciduous to tundra varj-ing according to altitude.
(iv) Mosses and lichens are common, while few trees grow here.	(iv) Rhododendron plants grow on most mountains. Oak, laurel and chestnut trees are also found up to 2000 m above sea-level. Pine trees are found up to 4000 m.
(v) The trees that do manage to grow stay close to the ground so they are insulated by snow during the cold winters.	(v) Above 4000 m altitude only lichens, grass and moss can be found.

Question 2.
Vegetation in Mediterranean and Temperate Deciduous Biome.
Answer:

Vegetation in the Mediterranean Biome	Vegetation in the Temperate Deciduous Biome
(i) The height of the trees is less.	(i) The vegetation has adapted to the cold climate.
(ii) The vegetation is mixed type, evergreen and deciduous.	(ii) They are found in three layers. Tall growing trees (18 m to 30 m), short trees and shrubs such as laurel and berries grows
(iii) The leaves of the trees are waxy and thick.	(iii) The trees have broad leaves.
(iv) The evaporation is less and they can sustain longer in tough conditions.	(iv) In this biome, hardwood and deciduous trees are found.
(v) Rosemary, cork, oak, olive, eucalyptus, peach, pine, sweet chestnut, cedar, Cyprus, etc., are found.	(v) Beech, elm, chestnut, oak, willow, cherry, maple, pine, walnut, deodar, etc., are found.

Answer the following question by using the given map.

Question 1.
Name the biome in Africa and Saudi Arabia.
Answer:
Tropical Desert biome

Question 2.
The continuous belt of which biome do you see in Russia?
Answer:
Taiga biome

Question 3.
Name the biome shown in Brazil in South America.
Answer:
Tropical Rainforest biome

Question 4.
Which biome is marked in the countries bordering the Mediterranean Sea?
Answer:
Mediterranean biome

Question 5.
Name the biome shown in India and its neighboring countries of SE Asia.
Answer:
Tropical Deciduous biome

Answer in detail.

Question 1.
Describe the Aquatic Biomes.
Answer:

1. Approximately, 70% of the earth’s surface is covered by oceans. Besides oceans, there are rivers, lakes, etc., which are freshwater sources.
2. Biomes are found in water, too. Here, the plants and animals have adapted themselves to the existing climatic conditions.
3. The aquatic biomes consist of any part of the earth that is covered with water, including fresh water and saltwater.
4. The aquatic biome can be further divided into freshwater biomes, marine biomes, wetland biomes, coral reef biomes, estuaries, etc., based on the salt content of the water and the aquatic plants that live there.

In the marine biomes, there are three layers:
(i) Euphotic Layer: It is found till a depth of 200 m and sunlight can reach here. It houses many fishes, sea turtles, jellyfish, seals, corals, zooplankton, and mangroves.

(ii) Disphotic Layer: It is the middle layer. Here, some light penetrates to the bottom part. It is around 1000 m deep from the mean sea level. Except for a few phytoplankton that has sunk from the upper layer, plants are not found here. Squid, cuttlefish, wolfish, swordfish, eels, sea dragons, etc., are found. These creatures are adapted to darkness, cold water, and high pressure.

(iii) Aphotic Layer: It is the third and the deepest layer that ranges from 1000 m to 4000 m depth. No light penetrates here. There is no living plant life. Inhabitants of this cold dark environment include elusive giant squid, bioluminescent jellyfish, angler fish, hatchet fish, etc. Sperm whales enter this zone to hunt but return to the upper layers.

Beyond this layer, lies the darkest and deepest zone extending up to the seafloor. Here, the animals are adapted to survive on detritus under even greater pressure.

Balbharti Maharashtra State Board Class 11 Geography Important Questions Chapter 7 Indian Ocean – Relief and Strategic Importance Important Questions and Answers.

Maharashtra State Board 11th Geography Important Questions Chapter 7 Indian Ocean – Relief and Strategic Importance

Complete the chain.

Question 1.

A	B	C
(1) Continental shelf	(1) Archipelagos formed by coral atolls	(1) Very wide on the western side of India
(2) Mid-Oceanic Ridges	(2) Portion of continent submerged underwater	(2) Ashmore
(3) Oceanic Plateaus	(3) Submerged mountain ranges that separate deep portions of the ocean floor	(3) the Ninety East Ridge
(4) Islands	(4) Deep flat areas on the ocean bottom	(4) Chagos

Answer:

A	B	C
(1) Continental shelf	(1) Portion of continents submerged underwater	(1) Very wide on the western side of India
(2) Mid-Oceanic Ridges	(2) Submerged mountain ranges that separate deep portions of the ocean floor	(2) Ninety East Ridge
(3) Oceanic Plateaus	(3) Deep flat areas on the ocean bottom	(3) Chagos
(4) Islands	(4) Archipelagos formed by coral atolls	(4) Ashmore

Complete the table.

Question 1.
The Indian Ocean bordered by

Sr. No	Direction	Continents / Oceans
(1)	West	—–
(2)	North and East	—–
(3)	East	—–
(4)	South	—–

Answer:

Sr. No	Direction	Continents / Oceans
(1)	West	Africa
(2)	North and East	Asia
(3)	East	Australia
(4)	South	Southern Ocean

Question 2.
Bottom Relief of the Indian Ocean

Sr. No	Features	Comprise of
(1)	Continental Shelf	—–
(2)	Mid-oceanic Ridges	—–
(3)	Ocean Basins	—–
(4)	Oceanic Deeps	—–
(5)	Islands	—–

Answer:

Sr. No	Features	Comprise of
(1)	Continental Shelf	Gulf, seas, bays and straits
(2)	Mid-oceanic Ridges	Submerged mountain ranges and plateaus
(3)	Ocean Basins	Terminal destinations for the sediments brought from the continents and from the oceanic part itself.
(4)	Oceanic Deeps	Deep, narrow and steeply sloping depressions found on the ocean floor
(5)	Islands	Coral atolls and volcanic islands

Question 3.
Islands of Indian Ocean

Sr. No	Islands of Indian Ocean:
(1)	Islands in the Arabian Sea	———
(2)	Islands of Bay of Bengal	———
(3)	Islands along Australian Coast	———

Answer:

Sr. No	Islands of Indian Ocean:
(1)	Islands in the Arabian Sea	Madagascar, Comoros, Bassas de India, Europa Island, Reunion, Maldives, Chagos, Mauritius, Seychelles, Island of Socotra, Lakshadweep, Bundle Island, Kish, Hendorabi, Lavan, Siri, etc.
(2)	Islands of Bay of Bengal	Sri Lanka, Andaman and Nicobar, Sumatra Island
(3)	Islands along Australian Coast	Ashmore, Christmas and Cocos (or Keeling) Island.

Choose the correct option by identifying the correct correlation in the sentences.

Question 1.
Most of the trenches of the Indian Ocean are located towards its ………………… boundary.
(a) northern
(b) southern
(c) eastern
(d) western
Answer:
(c) eastern

Question 2.
The Bundle Island is located near the coast of …………………….
(a) Sri Lanka
(b) Pakistan
(c) Bangladesh
(d) Myanmar
Answer:
(b) Pakistan

Question 3.
To the east of …………………. lie the islands like Reunion, Mauritius, Seychelles, Socotra.
(a) Madagascar
(b) Australia
(c) Indonesia
(d) Sri Lanka
Answer:
(a) Madagascar

Question 4.
Diego Garcia is an atoll which was first discovered by the Europeans and named by the ……………………
(a) Portuguese
(b) French
(c) Dutch
(d) Germans
Answer:
(a) Portuguese

Question 5.
The salinity of the oceans is generally …………………. around the Somali Peninsula and closer to the Saudi Arabian Coast.
(a) high
(b) low
(c) moderate
(d) very high
Answer:
(a) high

Question 6.
The South Equatorial current flows from / in the ……………………
(a) west to east
(b) east to west
(c) clockwise direction
(d) anticlockwise direction
Answer:
(b) east to west

Identify the correct correlation.

A : Assertion
R : Reasoning

Question 1.
A – There is a complete blockage of the Indian Ocean towards its north.
R – Unlike the Pacific Ocean and the Atlantic Ocean the Indian Ocean does not extend northwards to the Arctic Ocean.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(c) Both A and R are correct and R is the correct explanation of A.

Question 2.
A – It is believed by most of the geologists that Madagascar was a part of African Continent in the geological past.
R – It has undergone two separations such as first separation from Africa and later from the Indo-Australian Plate.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(c) Both A and R are correct and R is the correct explanation of A.

Question 3.
A – In the case of Bay of Bengal, the Peninsular rivers lead to the lowering of salinity in this area.
R – The salinity is less during the period of South West Monsoon.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(d) Both A and R are correct but R is not the correct explanation of A.

Question 4.
A – The Indian market has emerged as one of the largest importers of South East Asian goods.
R – The recently concluded Free Trade Agreements with countries like Thailand and Singapore are set to contribute to this trend.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(d) Both A and R are correct but R is not the correct explanation of A.

Identify the incorrect factor.

Question 1.
The islands in Bay of Bengal are-
(a) Andaman and Nicobar
(b) Sri Lanka
(c) Sumatra
(d) Madagascar
Answer:
(d) Madagascar

Question 2.
The islands in the Arabian Sea are-
(a) Sumatra
(b) Mauritius
(c) Seychelles
(d) Chagos
Answer:
(a) Sumatra

Question 3.
The islands along the Australian coast are-
(a) Maldives
(b) Ashmore
(c) Christmas
(d) Cocos
Answer:
(a) Maldives

Question 4.
Islands in the Arabian Sea along the Persian Gulf-
(a) Kish
(b) Siri
(c) Lavan
(d) Bundle
Answer:
(d) Bundle

Question 5.
Ocean basins in the Indian Ocean are-
(a) Andaman basin
(b) Somali basin
(c) Oman basin
(d) Mauritius basin
Answer:
(a) Andaman basin

Question 6.
The Ocean currents in southern part of the Indian Ocean are-
(a) South equatorial current
(b) West wind drift
(c) Northeast current
(d) Mozambique-Agulhas currents
Answer:
(c) Northeast current

Question 7.
Islands to the east of Madagascar island are-
(a) Mauritius
(b) Lavan
(c) Reunion
(d) Seychelles
Answer:
(b) Lavan

Question 8.
The islands in the Arabian Sea are-
(a) Comoros
(b) Bassas de India
(c) Europa island
(d) Sri Lanka
Answer:
(d) Sri Lanka

Question 9.
The busiest straits in the Indian Ocean are-
(a) Hormuz
(b) Malacca
(c) Bab-el-Mandeb
(d) Palk
Answer:
(d) Palk

Give geographical reasons.

Question 1.
Monsoon climate has developed in the Indian sub-continent.
Answer:
Monsoon climate has developed in the Indian sub-continent because-

1. The Indian Ocean spreads between Africa in the west, Asia in the north and east, Australia in the east and Southern Ocean in the south.
2. The Indian Ocean does not extend northwards to the Arctic Ocean like the Atlantic Ocean and the Pacific Ocean.
3. This has resulted in complete blockage of the Indian Ocean towards its north.
4. This peculiar arrangement of the ocean and the continental portion contributes a lot to the development of the monsoon climate of the Indian sub-continent.
5. During summer solstice, sun shines vertically on tropic of cancer, so there is summer season over the Indian sub-continent.
6. Due to continuous heating, low pressure area is created, moisture laden south west monsoon winds give rainfall on the Indian sub-continent, that is rainy season.
7. During winter solstice, due to slanting sunrays, the temperature goes down, that is winter season.
8. Thus, there is monsoon climate with three distinctive seasons.

Question 2.
The study of temperature of the ocean is essential.
Answer:
The study of temperature of the ocean is essential because-

1. The temperature of the ocean provides information on the global climate system.
2. It is also important for the study of marine ecosystems.
3. The temperature of the ocean water is responsible for the movement in the oceanic water.
4. Rising temperatures cause coral bleaching and loss of breeding grounds for marine fishes and mammals.
5. The study of temperature of the ocean can help in establishing marine protected areas and forming precautionary limits to prevent overfishing, protecting ocean ecosystems and shield humans from the effects of ocean warming.

Answer the following question by using the given map.

Question 1.
Name the plateau in South Indian Ocean.
Answer:
Kerguelen Plateau

Question 2.
Name the ocean basin in North Arabian Sea.
Answer:
Oman Basin

Question 3.
Name the ocean current near the equator in the Indian Ocean.
Answer:
Counter Equator Current

Question 4.
Name the ocean current in Western Indian Ocean.
Answer:
Agulhas Current

Question 5.
Name the ocean current in Eastern Indian Ocean.
Answer:
Australian Current

Write short notes on.

Question 1.
Challenges in the Indian Ocean
Answer:

1. India occupies a central and strategic location in the Indian Ocean.
2. Keeping the Indian Ocean as a Zone of Peace free from superpower rivalry is a major challenge in the Indian Ocean.
3. Most of the conflicts since the end of the Cold War have taken place in or around the Indian Ocean region. As a result, almost all the world’s major powers have deployed substantial military forces in the Indian Ocean region.
4. Expanding markets and larger import flows imply vulnerability at sea. Hence, the incidence of piracy, armed robbery and maritime terrorism are on the rise and has placed a premium on the complexity of Sea lane defence.

Question 2.
Islands in Indian Ocean
Answer:

1. There are 39 islands in the Indian Ocean. Most of them are away from the coastline. They are deep sea islands.
2. The islands of the Indian Ocean are a varied collection, including many smallest territories and some large islands like Sri Lanka, Australia and Madagascar.

The islands in the Indian Ocean are grouped into-

1. Islands of Arabian sea
2. Islands along Bay of Bengal
3. Islands along the Australian coast

Islands in Indian Ocean-

1. Islands of the Arabian Sea can be sub grouped such as islands close to the African coast and islands along the Lakshadweep – Chagos Ridge.
2. The largest island close to the African coast is Madagascar island. It is separated from Africa, and later from the Indo-Australian plate. It is one of the seismologically active provinces.
3. There are many islands between the eastern coast of Africa and Madagascar island, such as Comoros, Europa and Bassas de India, etc. To the east of Madagascar are Mauritius, Reunion and Seychelles, etc.
4. The group of islands along Lakshadweep-Chagos Ridge are Maldives, Chagos and Lakshadweep.
5. Apart from these islands, other islands are the Bundle island near the coast of Pakistan and Siri, Lavan, Kish, Hendorabi, etc., along the Persian Gulf part of Iran.
6. The islands in Bay of Bengal are associated with the converging plate boundary. These islands are the peaks of submerged mountains. The islands of Bay of Bengal are Sri Lanka, Andaman and Nicobar group, and chain of islands along the western coast of Sumatra island of Indonesia.
7. Most of these islands are volcanic islands. Sri Lanka is the largest island of this group.
8. There are very few islands along the coastline of Australia such as Cacos, Christmas, Ashmore, etc.

Answer in detail.

Question 1.
Describe the continental shelf of the Indian Ocean.
Answer:

1. The continental shelf is the portion of continents submerged under oceanic water.
2. It is normally occupied by different gulfs, seas, bays and straits.
3. There is a wide range of variation in the continental shelves of the Indian Ocean.
4. There are quite extensive shelves along the Indian coasts.
5. The eastern coast of Africa and Madagascar record relatively narrow width of continental shelves, and along the Indonesian coast, it is very narrow (160 km).
6. The continental shelves are very wide in the west of India whereas these are narrow along the eastern coast.
7. Continental shelves are veneered with deposits brought down by terrestrial agents of erosion.
8. Some of the sedimentary deposits are received from over thousand years.
9. As they remain deposited for a long time, sedimentary rocks are formed.
10. Some of them are a potential source of fossil fuel.

Question 2.
Describe the Mid-Oceanic Ridges of the Indian Ocean.
Answer:

1. Mid-oceanic ridges are submerged mountain ranges that separate deep portion of the sea (Ocean) floor.
2. The Indian Ocean has a Mid Ocean ridge called as a Mid Indian Oceanic Ridge.
3. It originates from the Gulf of Eden near the Peninsula of Somalia.
4. It further extends toward the south and on the eastern side of Madagascar, it divides into two branches.
5. One branch diverts towards southwest and extends up to Prince Edward Island. It is known as Southwest Indian Ocean Ridge.
6. The second branch extends south eastwards up to Amsterdam and St. Paul Island. It is known as Mid Indian Ocean Ridge.
7. Mid Indian Oceanic Ridge has many parallel ridges. This ridge is not continuous due to many fracture Zones in it. e.g. Owen Fracture Zone. Amsterdam Fracture Zone, etc.

Question 3.
Explain in detail the importance of Indian Ocean to India.
Answer:
India has the control and strategic location in the Indian Ocean. Therefore, India’s economic and national interests are linked with the Indian Ocean.

From economic point of view, India’s trade with neighbouring countries is dependent on the Indian Ocean. Indian Ocean provides major sea route connecting Middle East, Africa and East Asia with Europe and America. India’s import of mineral oil mainly comes from Gulf countries.

The sand on the beaches along the Arabian Sea is rich in valuable minerals like uranium. India has offshore deposits of mineral oil at Bombay High in the Arabian Sea. Abyssal plains of the Indian Ocean have deposit of polymetallic nodules. These nodules are source of nickel, copper, manganese and cobalt.

India has developed very good trade relations with countries of east due to its location along the Arabian Sea. Trade volumes with ASEAN countries are increasing every year. The Indian market has emerged as one of the largest importers of South East Asian goods. India also has Free Trade Agreements with Singapore and Thailand.

The northern area of the Indian Ocean is the area of great significance in economic and strategic terms. With expansion of India’s export and import, India is forecasted to become one of the three fastest growing economics in the world.

Due to heavy trade, through Indian Ocean, the incidences of piracy, armed robbery and maritime terrorism are on the rise and therefore, defence work in the Indian Ocean have increased.

To keep the Indian Ocean as a zone of peace, free from superpower rivalry and increasing cooperation among littoral countries in the region has always been India’s foreign policy goal. For example, Indian Ocean Rim Association for Regional Cooperation, Ganga-Mekong Cooperation, etc.

Balbharti Maharashtra State Board Class 11 Geography Important Questions Chapter 6 Ocean Resources Important Questions and Answers.

Maharashtra State Board 11th Geography Important Questions Chapter 6 Ocean Resources

Complete the chain.

Question 1.

A	B	C
(1) Continental Shelf	(1) Mariana Trench	(1) Methane Hydrate
(2) Continental Slope	(2) Mumbai High	(2) Coral Island
(3) Oceanic Ridges and Plateau	(3) Krishna-Godavari Basin	(3) Deepest Part
(4) Oceanic Trenches	(4) Aldabra	(4) Oil and Gas

Answer:

A	B	C
(1) Continental Shelf	(1) Mumbai High	(1) Oil and Gas
(2) Continental Slope	(2) Krishna-Godavari Basin	(2) Methane Hydrate
(3) Oceanic Ridges and Plateau	(3) Aldabra	(3) Coral Island
(4) Oceanic Trenches	(4) Mariana Trench	(4) Deepest Part

Choose the correct option by identifying the correct correlation in the sentences.

Question 1.
The phenomenon of tides releases ………………..
(a) large amounts of energy
(b) large amounts of sediments
(c) large amounts of forces
(d) large amounts of resources
Answer:
(a) large amounts of energy

Question 2.
Desalination process ………………..
(a) is the removal of oil from sea water
(b) is the removal of petroleum from sea water
(c) is the removal of salt from sea water
(d) is the removal of seaweeds from sea water
Answer:
(c) is the removal of salt from sea water

Question 3.
The gradient of slope of continental slope region can be ………………….
(a) around 2° to 5°
(b) between 12° to 15°
(c) around 2° to 4°
(d) between 2° to 5°
Answer:
(d) between 2° to 5°

Question 4.
The oceanic trenches generally occur along plate boundaries and are associated with …………………
(a) active volcanoes and strong earthquakes
(b) folds and fault
(c) sedimentation
(d) deep sea movements
Answer:
(a) active volcanoes and strong earthquakes

Question 5.
Limestones are formed extensively in the tropical oceans of the world as a result of ………………….
(a) volcanic heat
(b) precipitate material by corals and plants
(c) sediments brought by the rivers
(d) evaporation of sea water
Answer:
(b) precipitate material by corals and plants

Question 6.
On tropical coasts, ………………….. vegetation is found abundantly.
(a) evergreen
(b) mangrove
(c) deciduous
(d) coniferous
Answer:
(b) mangrove

Question 7.
The ……………….. Ocean route is the most important and busiest ocean route in the world.
(a) Atlantic
(b) Pacific
(c) Indian
(d) Arctic
Answer:
(a) Atlantic

Question 8.
The deposition of sediments is limited in ………………….
(a) Continental shelf
(b) Continental slope
(c) Abyssal plains
(d) Oceanic deeps
Answer:
(b) Continental slope

Question 9.
The submerged ……………….. on the ocean floor are called oceanic ridges.
(a) mountains
(b) Islands
(c) deeps
(d) plateaus
Answer:
(a) mountains

Question 10.
The ………………… are isolated habitats that have evolved slowly over millions of years to support communities.
(a) ridges
(b) mountains
(c) plateaus
(d) seamounts
Answer:
(d) seamounts

Identify the correct correlation.

A : Assertion
R : Reasoning

Question 1.
A – The oceanic trenches are the deepest parts of the oceans.
R – These trenches can be thousands of metres deep.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(c) Both A and R are correct and R is the correct explanation of A.

Identify the incorrect factor.

Question 1.
Continental Islands in India are-
(a) Minicoy
(b) Seven Islands of Bombay
(c) Amindivi
(d) Andaman
Answer:
(d) Andaman

Question 2.
The relief of ocean floor contain-
(a) depression
(b) continental shelf
(c) abyssal plain
(d) ocean trench
Answer:
(a) depression

Question 3.
The biotic resources on ocean floor are-
(a) plankton
(b) seaweeds
(c) minerals
(d) fish
Answer:
(c) minerals

Question 4.
The abiotic resources on ocean floor are-
(a) limestone
(b) mollusc
(c) gypsum
(d) mineral oils
Answer:
(b) mollusc

Question 5.
The biotic resources on ocean floor are-
(a) whale
(b) corals
(c) sodium chloride
(d) seahorse
Answer:
(c) sodium chloride

Question 6.
Abiotic resources on ocean floor are-
(a) shrimp
(b) potassium
(c) sodium chloride
(d) natural gas
Answer:
(a) shrimp

Question 7.
Marine pollution occurs due to-
(a) industrial effluents
(b) disposal of solid waste
(c) leakage of oil from oil exporting ships
(d) burning of waste
Answer:
(d) burning of waste

Question 8.
The richest Ashing grounds in the world are-
(a) Dogger bank
(b) Konkan coast
(c) Grand bank
(d) Georges bank
Answer:
(b) Konkan coast

Give geographical reasons.

Question 1.
The very existence of marine life is threatened.
Answer:
The very existence of marine life is threatened because-

1. Due to human activities, the ocean is polluted on a large scale.
2. The leakages of oil from oil transporting ships, oil extraction from coastal areas, disposal of solid waste containing radioactive matter, atomic tests etc., are causing large scale pollution of oceanic waters.
3. The effluents brought by river discharges, the disposal of waste from coastal cities, the waste from industries and many other similar factors are polluting the oceanic waters.

Question 2.
The seas and oceans are the most convenient natural medium of transport.
Answer:
The seas and oceans are the most convenient natural media of transport because-

1. Sea or ocean transport is used for both passengers and goods transport.
2. The most important aspect of sea and ocean transport is that it is the cheapest mode of transport than any other modes of transport.
3. The heavy goods, machinery, vehicles etc., can be carried by ocean transport conveniently and at cheaper rate.
4. The transport of goods and passengers between the countries is not possible by rail and road transport, air transport has limitations; therefore, sea or ocean transport is useful and convenient for international trade.
5. For example, Suez Canal connects the Mediterranean Sea to the Indian Ocean via. the Red Sea, making it the shortest maritime route to Asia from Europe.

Question 3.
Ocean tourism is becoming popular.
Answer:
Ocean tourism is becoming popular because-

1. Ocean tourism is developed along the coastal areas of seas and oceans.
2. Generally, water sports activities such as scuba diving, surfing, water skiing, etc., are developed along the coastline. For example, sport activities along the coast of Goa.
3. There is a beautiful scenery along the coastline due to greenery of trees.
4. Along the coast we find huge water bodies of seas and oceans, clean air and coolness due to nearness to water. Therefore, many resorts, hotels, marina, etc., are developed and coastal areas have become popular for tourism.
5. The cruise tourism is also increasing.

Differentiate between.

Question 1.
Continental Shelf and Continental Slope.
Answer:

Continental Shelf	Continental Slope
(i) The portion of the continents that is submerged under water and borders the coastal areas is known as a continental shelf.	(i) After the extent of continental shelf is over, there is a sharp drop in the ocean floor. This is called continental slope.
(ii) They are broad, shallow and gently-sloping plains covered by water.	(ii) The slope is steep and stretches over limited area.
(iii) The depth of the continental shelf from the sea level is about 180 to 200 m.	(iii) The depth of the continental slope is from 200 m to 4000 m from the sea level.
(iv) Sunlight reaches up to the bottom of the continental shelf and hence fishing is done on a large scale in this region.	(iv) Sunlight does not reach the bottom of the continental slope and moreover due to the steep slope fishing cannot be done in this region.
(v) The continental shelves contain the world’s largest reservoirs of natural oil and gas. Besides oil and gas, minerals are also found here. Diamonds, chromite, ilmenite, magnetite, platinum, gold and phosphorite deposits are also found here. Sand, gravel aggregates and industrial silica sand are the most important of hard minerals now extracted in the near offshore zone.	(v) Methane hydrate, a compound of water and methane, is present on the continental slopes. On the slope, we find many traces of submarine landslide activity, ocean canyons and huge avalanche fans.

Question 2.
Oceanic Deeps and Oceanic Trenches.
Answer:

Oceanic Deeps	Oceanic Trenches
(i) At places, deep, narrow and steeply sloping depressions are found on the ocean floor. The shallow depressions are called deeps.	(i) At places, deep, narrow and steeply sloping depressions are found on the ocean floor. The deeper depressions are called ocean trenches.
(ii) Active volcanoes and earthquakes are not seen in oceanic deeps.	(ii) Trenches are formed at convergent plate boundaries. Active volcanoes and earthquakes generally occur along the plate boundaries of oceanic trenches.
(iii) The Romanche Trench in the Atlantic Ocean close to the equator.	(iii) The Mariana Trench in the Pacific Ocean is 11 kms deep.

Answer the following question by using the given map.

Question 1.
In which ocean are the Madagascar islands located?
Answer:
Madagascar islands are located in the Indian Ocean.

Question 2.
Mention the location of Georges Bank.
Answer:
Georges Bank is located along the north eastern coastline of U.S.A.

Question 3.
Where is the Congo Canyon located?
Answer:
The Congo Canyon is located along the western coastline of South Africa.

Question 4.
Name the group of islands located in the Pacific Ocean.
Answer:
The Hawaiian Islands are located in the Pacific Ocean.

Question 5.
Name the deepest trench in the Indian ocean.
Answer:
The deepest trench in the Indian Ocean is the Java Trench.

Write short notes on.

Question 1.
Causes of climate change
Answer:
The portion of the continents that are submerged under water and borders the coastal areas is known as a continental shelf.

They are broad, shallow and gently-sloping plains covered by water.

The continental shelf does not extend into the ocean uniformly. Near some coasts, it is narrow while in some parts it may extend for hundreds of kilometres. For example, they are almost absent or very narrow along the coasts of Chile, Sumatra etc., while the Siberian coast near the Arctic Ocean is around 1500 km in width.

Generally, its depth from the sea level is about 180 m to 200 m.

As the sunlight reaches this part of the ocean bed, it is rich in plankton. These millions of microscopic organisms found in sea water are an important food for fish. Millions of fishes thrive here. The shelf has some of the richest fishing grounds in the world, such as the Grand Banks and Georges Bank in North America.

The continental shelves contain the world’s largest reservoirs of natural oil and gas. For example, the Mumbai High in Arabian sea. Besides oil and gas, minerals are also found here.

Diamonds, chromite, ilmenite, magnetite, platinum, gold and phosphorite deposits are common. Sand, gravel aggregates and industrial silica sand are the most important of hard minerals now extracted in the near offshore zone.

Question 2.
Desalination
Answer:

1. Sea water contains lot of salt, so it is not useful for drinking or irrigation purpose. Therefore, it is necessary to convert the sea water into fresh water.
2. Desalination is the process of removal of salt from sea water and converting sea water into fresh water.
3. Desalination is done by heating water or freezing water or by electrical processes.
4. The desalination process is very expensive, therefore it is used where there is acute shortage of water.
5. The Minjur Desalination Plant is the largest in India, located at Kattupalli village, a northern suburb of Chennai on the coast of the Bay of Bengal that supplies water to the city of Chennai.
6. These desalination plants are more used in developing countries since the cost for processing is high. Desalination plants are located in Saudi Arabia, Oman, Cyprus, Algeria, Spain and UAE.
7. Desalination plants have adverse effect on the coastal environment. Small sea organisms like plankton and baby fish may be killed. Their food chain is disturbed.
8. It is still used in some countries to get fresh water.

Draw a neat and labelled diagram of the ocean floor.

Answer:

Answer in detail.

Question 1.
Explain uses of the oceans for other purposes.
Answer:
Following are the other uses of oceans:
For energy:

1. Tidal Energy : The phenomenon of tides releases large amounts of energy. Thus, tidal energy can be used to generate electricity.
2. Thermal energy : The temperature differences of sea water help in generating the energy. The surface water of the tropical region may have 25°C to 30°C of temperature while the deep-sea water may have less than 5°C. This gradient of temperature is used to run a generator to produce electricity.

For drinking water : Due to high salt content in sea water, it is not suitable for drinking or for irrigation directly. But sea water can be converted into fresh water.

Trade and transport : Maritime transport is the transport of people or cargo by water. Transportation by water is cheaper than any other modes of transport. The seas and oceans are the most convenient natural medium for transport. For example, Suez Canal connects the Mediterranean Sea to the Indian Ocean via. the Red Sea, making it the shortest maritime route to Asia from Europe.

Tourism : Ocean tourism comes in many forms like cruises, scuba-diving, fishing, beach tourism, etc. Such activities are increasingly becoming popular. In many areas, massive new tourist developments have been built which include resorts and marinas. These activities, in turn, affect the ocean habitats and environment.

Question 2.
Explain the biotic resources on the ocean floor.
Answer:

1. The biotic resources on the ocean floor bottom include plants and animals.
2. The oceans provide habitat to thousands of species of marine plants and animals which are food for many organisms.
3. There are many marine animals like fish, crabs, mollusks tortoises, prawns, etc.
4. There are many plant varieties such as seaweeds, mangroves, medicinal plants, and many more marine plants.
5. Many sea animals provide oil, leather, cattle feed, glue, and some other products. Seaweeds are also used as food. Seaweeds added in fertilizers and skincare ointments, etc.
6. Mangrove forests provide wood for fuel, furniture, and various products useful for man. Mangroves provide food and shelter to marine life.
7. There are also micro-organisms that produce organic material, they are called plankton. Plankton is one of the favourite fish foods. Marine life depends upon plankton.
8. Coral reefs are a major part of the ocean ecosystem. Tourism develops in the areas where corals are found. For example, the Great Barrier Reef in Australia attracts tourists from all around the world.

Thus, biotic resources on the ocean floor are valuable.

Question 3.
Explain the importance of abiotic resources on the ocean floor.
Answer:

1. There are many abiotic resources on the ocean floor and most of them are not exploited yet.
2. The most common resources are sodium chloride, gypsum, limestone, etc. Sodium chloride is a common salt.
3. Gypsum deposits are collected from the ocean floor. Gypsum is used in making Plaster of Paris.
4. The material which precipitates from the body of corals results in the formation of limestone. The metamorphic form of limestone is a marble.
5. A large number of metallic and non-metallic minerals are found on the ocean floor. These are rich deposits of copper, manganese, zinc, cobalt, platinum, etc.
6. The most important mineral related to our day-to-day life is extracted from the seafloor, that is mineral oil and natural gas. For example, Bombay High – is an oil mining area in the Arabian Sea.
7. When we obtain non-biotic resources from the ocean floor, it may cause a disturbance in ecological balance. The drilling machines may disturb marine organisms. Therefore, care should be taken to maintain the ecological balance of the ocean environment.

Balbharti Maharashtra State Board Class 11 Geography Important Questions Chapter 5 Global Climate Change Important Questions and Answers.

Maharashtra State Board 11th Geography Important Questions Chapter 5 Global Climate Change

Complete the chain

Question 1.

A	B	C
(1) Different density of corals in summer and winter	(1) Ice cores	(1) Understanding of past environmental conditions
(2) Variation in environmental conditions	(2) Goldilocks Zone	(2) Summer snow different from winter snow
(3) Samples of ice from inner sides of the ice sheets	(3) Creates seasonal growth rings on corals	(3) Earth was cooler when it was located in the outer reaches of this zone
(4) Habitable zone in which the Earth lies	(4) Tree rings	(4) Determines the temperature of water and season in which coral grew

Answer:

A	B	C
(1) Different density of corals in summer and winter	(1) Creates seasonal growth rings on corals	(1) Determines the temperature of water and season in which coral grew
(2) Variation in environmental conditions	(2) Tree rings	(2) Understanding ofpast environmental condition
(3) Samples of ice from inner sides of the ice sheets	(3) Ice cores	(3) Summer snow different from winter snow
(4) Habitable zone in which the Earth lies	(4) Goldilocks Zone	(4) Earth was cooler when it was located in the outer reaches of this zone

Choose the correct option by identifying the correct correlation in the sentences.

Question 1.
Urban areas heat up more readily because …………………..
(a) of presence of deserts
(b) of paved surfaces and concrete constructions
(c) they have many industries
(d) they are in plain regions
Answer:
(b) of paved surfaces and concrete constructions

Question 2.
Global sea level rise is apparently being caused because of …………………….
(a) increased melting of ice such as glaciers and ice sheets
(b) frequent flooding of coastal areas
(c) increase in precipitation
(d) flash floods
Answer:
(a) increased melting of ice such as glaciers and ice sheets

Question 3.
Around the world the jellyfish seem to be reproducing heavily and congregating in places because of ………………
(a) melting of ice sheets
(b) global warming
(c) sea water is rising
(d) warmer waters and changes in the acidity level of the oceans.
Answer:
(d) warmer waters and changes in the acidity level of the oceans.

Question 4.
These has been an increase in number of flash floods and also the duration of floods because of ……………….
(a) increased deforestation
(b) melting of glaciers
(c) very high precipitation in one day
(d) increase of volume of water in rivers
Answer:
(c) very high precipitation in one day

Question 5.
It has been observed that with more CO₂, in the air, crop yield has …………………
(a) increased
(b) decreased
(c) remained constant
(d) changed
Answer:
(a) increased

Question 6.
The average temperature of earth is around …………………
(a) 10°C
(b) 12°C
(c) 14°C
(d) 16°C
Answer:
(c) 14°C

Question 7.
Receding glaciers as a symptom of global climate change has been observed in the glaciers near ………………. in Africa.
(a) Mt. Kilimanjaro
(b) Mt. Kenya
(c) Mt. Meru
(d) Mt. Toubkal
Answer:
(a) Mt. Kilimanjaro

Question 8.
An increase of 1° – 2°C in ocean temperatures for a long time can lead to …………………. of corals.
(a) growth
(b) bleaching
(c) death
(d) congregation
Answer:
(b) bleaching

Question 9.
The roots of both flooding and drought lie in the physical process known as …………………
(a) erosion
(b) transportation
(c) deposition
(d) evaporation
Answer:
(d) evaporation

Question 10.
The ………………… in the trees provide clues about wet and dry periods.
(a) branches
(b) wood
(c) rings
(d) leaves
Answer:
(c) rings

Identify the correct correlation.

A : Assertion
R : Reasoning

Question 1.
A – India has high vulnerabilities to climate change.
R – India has peculiar economy and geography.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(d) Both A and R are correct but R is not the correct explanation of A.

Question 2.
A – More than one-fifth of the coral reefs are already lost.
R – Coral bleaching leads to death of large amount of corals.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(d) Both A and R are correct but R is not the correct explanation of A.

Question 3.
A – Coral formed in the summer has a different density than coral formed in the winter.
R – Summer snow differs from winters snow.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(d) Both A and R are correct but R is not the correct explanation of A.

Question 4.
A – Volcanism is considered as a cause of climate change.
R – The winds spread aerosols around the world reducing sun’s radiation to reach on earth’s surface.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(d) Both A and R are correct but R is not the correct explanation of A.

Question 5.
A – Higher sea levels may lead to deadlier cyclones and also frequent flooding of coastal areas.
R – High precipitation leads to higher sea level.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(a) Only A is correct.

Identify the incorrect factor.

Question 1.
Causes of climate change-
(a) Melting of glaciers
(b) Amount of energy
(c) Milankovitch oscillations
(d) Volcanism
Answer:
(a) Melting of glaciers

Question 2.
Some indirect effects of warming up of earth-
(a) Spread of insects in newer region
(b) Sea level rise
(c) Bleaching of corals
(d) Heavy reproduction of jellyfish
Answer:
(b) Sea level rise

Question 3.
Effects of global warming are-
(a) Heat wave
(b) Increase in sea level
(c) Heat islands
(d) Deforestation
Answer:
(d) Deforestation

Give geographical reasons.

Question 1.
Man and his activities are the major cause of climate change.
Answer:
Man and his activities are major cause of climate change because-

1. Besides natural causes there is an anthropogenic effect on the climate.
2. Due to human activities many greenhouse gases mainly Carbon Dioxide (CO₂) is released in the atmosphere.
3. The emission of CO₂ mainly comes from fossil fuel combustion.
4. Large scale deforestation also increases CO₂.
5. The atmosphere takes around 20 to 25 years to adjust these high levels of CO₂.

Question 2.
The change in climate is a natural and continuous process.
Answer:

1. The change in climate is a natural and continuous process because-
2. The earth has witnessed many variations in climate since the beginning.
3. There are various geological records that show alteration of glacial and inter-glacial periods.
4. The sediment deposits in glacial lakes also reveal the occurrence of warm and cold periods.
5. The rings in the trees provide clues about wet and dry periods.
6. Historical records describe the variations in climate.
7. All these evidences indicate that change in climate is a natural and continuous process.

Question 3.
Rainforest play a major role in cooling the earth.
Answer:
Rainforest play a major role in cooling the earth because-

1. Dense forest has a direct effect on the temperature of that area.
2. In moist tropical region there is dense forest growth, they form canopy. The broad leaves of the forest help to trap moisture and allow it to evaporate, so there is natural cooling effect.
3. When these forests are slashed and burnt over large area, hot and dry air spreads and the temperature of the area increases.
4. When forests are burnt, large amount of carbon dioxide is added to the atmosphere and there is air pollution, which also leads to global warming.
5. Heavy deforestation leads to decrease in the rainfall of that area and changes in rainfall pattern are observed.

Write short notes on.

Question 1.
Greenhouse gases
Answer:

1. Greenhouse gases are the primary gases, such as, water vapour carbon dioxide, nitrous oxide, methane and ozone in the earth’s atmosphere that absorbs and traps energy from the sun.
2. Of all greenhouse gases, carbon dioxide absorbs more heat.
3. Without greenhouse gases, the average temperature of the earth’s surface would be about -18°C rather than the present average of 14°C.
4. Carbon dioxide emissions comes from many human activities such as combustion of fossil fuels, oil and natural gas, with additional contributions coming from deforestation, changes in land use, soil erosion and agriculture (including live stock).

Question 2.
Causes of climate change
Answer:
Though human activities are a major cause for climate change, some natural causes are responsible for climate change. Following are some of the natural causes of climate change:
The amount of energy output by the sun is not the same always. Low energy output by sun can reduce amount of insolation received by the earth. This can lead to cooling of earth.

Another cause is the Milankovitch oscillation. Variations in the earth’s orbital characteristics around the sun and the changes in the earth’s axial tilt occur. These factors cause the earth to be closer to the sun (warmer) or farther from the sun (colder). Ice ages can occur when we are farther from the sun.

Volcanism is considered as another cause for climate change. Volcanic eruptions throw lots of particulates, and aerosols into the atmosphere. The winds spread it around the world reducing the sun’s radiation reaching the earth’s surface.

The habitable zone of the earth is called Goldilocks Zone. It means as the size of the sun increases, the zone moves outwards overtime. Such changes in zone causes earth to warm or cool.

Besides natural causes, anthropogenic activities affect the climate. The emission of CO₂ from fossil fuel combustion. Large-scale deforesting also increases CO₂. It takes around 20 to 25 years to adjust these high levels of CO₂.

Answer in detail.

Question 1.
Explain the effects global warming.
Answer:
The average temperature of the Earth is around 14°C. As given in the earlier graph, this average temperature has increased by 0.8° C. However, the following are the effects of global warming.

Heat waves:

1. Increase in the heat holding capacity of the atmosphere increases the temperature especially during summers.
2. Summers can become more intense or even deadlier and could bring hot spells.

Heat islands:

1. Global warming serves as a base from which heat waves become much worse – especially in big cities where the heat island effect comes into play.
2. Urban areas heat up more readily because of paved surface and concrete constructions as compared to a field or forest areas.

Increase in sea level:

1. Due to increased melting of ice such as glaciers and ice sheets, there is a global rise in the sea level every year.
2. Higher sea levels may lead to deadlier cyclones and also frequent flooding of coastal areas.
3. Many islands are also at risk of getting submerged.
4. It may result in saline coastal groundwater endangered wetlands and flooding of cities and coastal communities. For example, Mumbai and parts of Konkan coastline.
5. It also means loss of habitat for fish, birds and plants.
6. As per the studies carried out by the Indian National Centre for Ocean Information Services, sea level may rise 9 to 90 cm between 1900 and 2100.

Melting of glaciers at high altitudes and snow in polar areas:

1. Melting of glaciers is a natural process, but when glaciers and iceberg melt at an alarming rate, it is a cause of concern.
2. Retreating of glaciers is considered as a symptom of global climate change. This means there is lesser ice formation each year than of melting.
3. Over the last 25 years, Gangotri glacier has retreated more than 850 meters, with a recession of 76 meters from 1996 to 1999.

Other factors:

1. Around the world the jellyfish seem to be reproducing heavily and congregating in places where they were never seen before.
2. This happens because of warmer waters and changes in the acidity level of the oceans.
3. Spread of insects in newer region apparently increases the number of mosquitoes.
4. Bleaching of the corals take place due to increase in the ocean temperatures. Coral bleaching leads to death of large numbers of corals.

Question 2.
Explain the various tools for studying climate change.
Answer:
Scientists and meteorologists have been using instruments to measure climate and weather for the past 140 years. However, millions of years ago historical evidence called proxy data, which includes coral reefs, tree rings, ice cores, etc., were used to tell about the climate.
Coral reefs:

1. Coral reefs are very sensitive to changes in climate.
2. Corals form skeletons by extracting calcium carbonate from the ocean waters.
3. When the temperature changes, densities of calcium carbonate in the skeletons also change.
4. Coral formed in the summer has a different density than coral formed in the winter.
5. This creates seasonal growth rings on the corals.
6. Scientists can study these rings to determine the temperature of the water and the season in which the coral grew.

Tree rings:

1. Variation in these rings is due to variation in the environmental conditions when they were formed.
2. Thus, studying this variation leads to improved understanding of past environmental conditions.

Ice cores:

1. These are samples of ice taken from the inner sides of the ice sheets.
2. Throughput each year, layers of snow fall over the ice sheets in Greenland and Antarctica.
3. Each layer of snow is different.
4. Summer snow differs from winter snow.
5. Each layer gives scientists a lot of information about the climate each year.

Balbharti Maharashtra State Board Class 11 Geography Important Questions Chapter 4 Climatic Regions Important Questions and Answers.

Maharashtra State Board 11th Geography Important Questions Chapter 4 Climatic Regions

Complete the chain.

Question 1.

A	B	C	D
(1) Mediterranean climate	(1) Interior area of Asia	(1) Hot summer, very low rainfall	(1) Coniferous forest
(2) Equatorial rainforest climate	(2) Scandinavian countries and Siberia	(2) Cool summer, bitterly cold winters	(2) Scrubs and hardwood forest
(3) Tropical desert climate	(3) Amazon and Congo basins	(3) Moist winter and warm summer	(3) Dense and evergreen hardwood forest
(4) Taiga climate	(4) Central California and South Africa	(4) High temperature and convectional rainfall	(4) Xerophytic vegetation

Answer:

A	B	C	D
(1) Mediterranean climate	(4) Central California and South Africa	(1) Moist winter and warm summer	(1) Scrubs and hardwood forest
(2) Equatorial rainforest climate	(3) Amazon and Congo basins	(2) High temperature and convectional rainfall	(2) Dense and evergreen hardwood forest
(3) Tropical desert climate	(1) Interior area of Asia	(3) Hot summer, very low rainfall	(3) Xerophytic vegetation
(4) Taiga climate	(2) Scandinavian countries and Siberia	(4) Cool summer, bitterly cold winters	(4) Coniferous forest

Question 2.

A	B	C	D
(1) Tropical monsoon climate	(1) Between 10° and 20° N and S	(1) Summer temperatures around 35°C, rainfall averaging 250-1000 mm	(1) Tundra vegetation
(2) Tundra climate	(2) Between 45° to 65° N and S	(2) precipitation 500 to 2500 mm	(2) Tali thick grass with scattered trees
(3) Tropical savannah type of climate	(3) 65° to 90° N	(3) Summer temperature 27° to 32°, orographic rainfall	(3) Year-round short green grass, trees shed leaves in winter
(4) West European type	(4) Between 10° to 20° N and S	(4) Summer temperature 10°C! and winter temperature -20°C to -30°C	(4) Deciduous forest

Answer:

A	B	C	D
(1) Tropical monsoon climate	(1) Between 10° to 30° N and S	(1) Summer temperature 27° to 32°, orographic rainfall	(1) Deciduous forest
(2) Tundra climate	(2) Between 65° to 90° N	(2) Summer temperature 10°C and winter temperature -20°C to -30°C	(2) Tundra vegetation
(3) Tropical Savannah type of climate	(3) Between 10° to 20° N and S	(3) Summer temperatures around 35°C, rainfall averaging 250-1000 mm	(3) Tall thick grass with scattered trees
(4) West European type	(4) Between 45° to 65° N and S	(4) Mild cool summer, precipitation 500 to 2500 mm	(4) Year round short green grass, trees shed leaves in winter

Choose the correct option by identifying the correct correlation in the sentences.

Question 1.
Bushmen tribe is found in ……………….
(a) Tropical deserts
(b) Highland
(c) Ice sheet
(d) Tundra
Answer:
(a) Tropical deserts

Question 2.
In Marine West European type climate …………………
(a) trees shed leaves during summers
(b) no vegetation
(c) swamps during melting of show
(d) trees shed leaves during winter
Answer:
(d) trees shed leaves during winter

Question 3.
Tundra climate is observed in the belt from ……………………
(a) near poles in both hemispheres
(b) 65° to 90° North
(c) 20° to 30° in both hemispheres
(d) 0° to 10° in both hemispheres
Answer:
(b) 65° to 90° North

Question 4.
Rainforest dense vegetation is …………………… layered vegetation.
(a) two
(b) three
(c) four
(d) one
Answer:
(b) three

Question 5.
Tropical monsoon climate is found within …………….. North and South of the equator.
(a) 10° to 30°
(b) 0° to 10°
(c) 30° to 60°
(d) 60° to 90
Answer:
(a) 10° to 30°

Question 6.
In India parts of the peninsular plateau and rain-shadow zone in Maharashtra has …………………. type of climate.
(a) Mediterranean
(b) Arid
(c) Tropical Savannah
(d) Mountain
Answer:
(c) Tropical Savannah

Question 7.
Rainfall in winter is a characteristic of …………………. climate.
(a) China type
(b) Marine West European
(c) Taiga
(d) Mediterranean
Answer:
(d) Mediterranean

Question 8.
The tribes of Greenland are ……………….
(a) Aborigines
(b) Inuits
(c) Bushmen
(d) Bedouin
Answer:
(b) Inuits

Question 9.
Terrace cultivation is a characteristic of ………………….. type of climate.
(a) mountain
(b) ice cap
(c) equatorial
(d) arid
Answer:
(a) mountain

Identify the correct correlation.

A : Assertion
R : Reasoning

Question 1.
A – In high mountains, large changes in mean temperatures occur over short distances.
R – Highland climates are governed by topography.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(c) Both A and R are correct and R is the correct explanation of A.

Question 2.
A – In ice cap climate extremely meagre precipitation in the form of snow is found.
R – Precipitation exceeds evaporation.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(d) Both A and R are correct but R is not the correct explanation of A.

Question 3.
A – In Tundra region, the winter temperature is not as severe as the Taiga.
R – The Tundra is closer to the sea while Taiga is away from any ocean body.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(c) Both A and R are correct and R is the correct explanation of A.

Question 4.
A – In southern hemisphere permanent settlements are found around Taiga region.
R – Latitudinal location plays a great role in the climate.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(b) Only R is correct.

A – Rainforest are dense.
R – Constant high temperature and heavy convectional rainfall evenly distributed over the year.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(c) Both A and R are correct and R is the correct explanation of A.

Identify the incorrect factor.

Question 1.
Equatorial rainforests are observed in-
(a) Congo and Amazon basin
(b) Indonesia
(c) Malaysia
(d) South East Asia
Answer:
(d) South East Asia

Question 2.
Tropical desert or arid type climate is observed in-
(a) Philippines
(b) Rajasthan
(c) Coastal Chile
(d) Peru
Answer:
(a) Philippines

Question 3.
In China type or humid sub-tropical climate the following crops are grown-
(a) olives
(b) citrus fruits
(c) cotton
(d) tobacco
Answer:
(a) olives

Question 4.
In ice sheet regions the characteristics of climate is-
(a) snowfall
(b) frequent anticyclones
(c) precipitation exceeds evaporation
(d) winter rainfall
Answer:
(c) precipitation exceeds evaporation

Question 5.
The characteristics of the climate in tropical desert regions are-
(a) high humidity
(b) highest diurnal range of temperature
(c) precipitation less than 200 mm
(d) windy conditions
Answer:
(a) high humidity

Question 6.
The characteristics of the Mediterranean climate regions are-
(a) mild, moist winter
(b) warm, dry summer
(c) drizzle
(d) foggy coasts
Answer:
(c) drizzle

Question 7.
The characteristics of the China type climate regions are-
(a) frost in winter
(b) windy condition
(c) summer temperature 10°C
(d) winter temperature 0°C to 18°C
Answer:
(b) windy condition

Question 8.
The Taiga type of climate is observed in-
(a) New Zealand
(b) Scandinavian countries
(c) Northern part of North America
(d) Siberia
Answer:
(a) New Zealand

Question 9.
The Marine North Western type of climate is observed in-
(a) Siberia
(b) Canada
(c) New Zealand
(d) Australia
Answer:
(a) Siberia

Question 10.
The main economic activities of people in Tundra region is-
(a) hunting and fishing
(b) lumbering
(c) animal rearing
(d) mining
Answer:
(b) lumbering

Complete the table.

Answer:

Identify the correct Group

Question 1.
Tropical Monsoon climate.
(A) Within 0° to 10° N and S of equator
High annual rainy temperature
Rainfall 250 to 2500 mm.
Saline soil

(B) Within 10° to 30° N and S of equator
High annual range of temperature
Rainfall 250 to 2500 mm.
Iron rich soil in high rainfall zones

(C) Between 10° to 20° N and S latitude
High diurnal range of temperature
Rainfall 250 to 1000 mm.
Swamps

(D) Between 20° to 30° N and S latitude
High diurnal temperature
Scanty rainfall
Sandy soil
Answer:
B

Question 2.
Mediterranean climate regions.
(A) Central California
South and South West Australia
Cape Town
Central Part of Chile

(B) Canada
Western Europe
South East Australia
New Zealand

(C) Between 10° to 20° N and S latitude
High diurnal range of temperature
Rainfall 250 to 1000 mm.
Swamps

(D) Between 20° to 30° N and S latitude
High diurnal temperature
Scanty rainfall
Sandy soil
Answer:
A

Give geographical reasons.

Question 1.
Most natural regions are homogeneous ecosystem.
Answer:

1. A natural region is a region which has common natural factors related to geography, geology and climate such as vegetation, animal resources etc.
2. A natural region has same flora and fauna. For example, in tropical desert region xerophytes grow everywhere due to low rainfall resulting into shortage of water supply.
3. From ecological point of view, the naturally available flora and fauna of this region are influenced by geographical as well as geological factors such as temperature, rainfall, soil. etc.
4. Thus, most of the natural regions are homogeneous ecosystem.

Differentiate between.

Question 1.
Tropical Monsoon and Tropical Desert type of climate.
Answer:

	Tropical Monsoon	Tropical Desert
Latitudinal extent	Within 10° to 30° North and South.	Found usually between 20° to 30° latitudes in both hemispheres.
Temperature	Summer temperature is around 27°C to 32°C while winter temperature is 15°C to 24°C.	Summer temperature around 30°C to 45°C, winter temperature around 20°C to 25°C.
Rainfall	Rainfall is between 250 to 2500 mm, excessively wet during rainy season.	Precipitation less than 200 mm.
Vegetation	Tropical rainforest, ranges from jungles to thorn forest in drier boundaries.	Xerophytic plants are found which can withstand extreme temperature.
Animal life	Large hooved leaf eaters and large carnivores like tigers.	Small, nocturnal, burrowing animals are found.
Human life	Agriculture is the main occupation of people of monsoon region.	Agriculture is practiced near oasis.
Regions of the world	Coastal areas of South West India and South East Asia, South West Africa, North East and South East Brazil, Northern part of Australia and part of Japan come under the monsoon winds.	Western coasts of all continents, large parts of Gujarat, Rajasthan and South West Haryana, Iran, interior parts of Asia, Coastal Chile, Peru, South-west Africa, interior Mexico, Baja California, North Africa, Namibia and parts of US.

Equatorial Rainforests and Savannah Climatic Regions.

Taiga region
(7) Monsoon region
(8) Greenland
(9) Equatorial region
Answer:

Answer the following question by using the given map.

Question 1.
Name the climatic region along Mediterranean Sea.
Answer:
Mediterranean type of climate region.

Question 2.
Name the climate region along NW coast of Europe.
Answer:
West European type of climate region.

Question 3.
Name the island which has Ice sheet.
Answer:
Greenland island.

Question 4.
In which part of China, Chine type of climate is found?
Answer:
South eastern part of China.

Question 5.
Name the countries where Tundra type of climate is found.
Answer:
Northern part of Russia and Northern part of Canada and Alaska.

Write short notes on.

Question 1.
Equatorial Rainforest
Answer:
Equatorial region is located between 0° to 10° in both the hemisphere, that is on either side of the equator.

The Amazon basin of South America, Congo basin of Africa, East coast of Central America, Malaysia, Indonesia, Papua New Guinea, Madagascar, Philippines are included in this region.

This region has a unique climate. Being located along the equator, sunrays are vertical throughout the year. Therefore, the temperature is constantly high throughout the year, Average

The days and nights are of equal duration. This may be the only region in the world where there is no summer or winter seasons. Throughout the year there is high temperature and heavy rainfall, thus it has hot and wet climate.

This region has heavy rainfall almost daily. The ITCZ (Inter-Tropical Convergence Zone) is an area of low pressure in this region due to high temperature and convectional currents. In ITCZ, North East and South East trade winds converge. They bring warm and humid air in this region. Due to convectional currents, moist air rises up, gets condensed and gives heavy rainfall every day. Rainfall is 2500 to 3000 mm, evenly distributed over the year.

Due to hot and wet climate, there is a luxuriant growth of the trees. Therefore, the trees are tall and forest have three layered vegetation. Due to heavy rainfall trees are evergreen. Thus, they are evergreen rainforest and they provide hardwood.

Due to dense forest growth, climbing and jumping animals like monkeys, as well as snakes, crocodiles are observed on marshy land. This region has rich biodiversity.

Due to heavy rainfall chemical weathering is more common than physical weathering, fertile elements of soil are washed away. only iron particles remain in the soil.

Tribal people live in this region with the help of hunting of birds and animals and food gathering activity. For example, pygmies in Congo basin of Africa.

Question 2.
Tundra region
Answer:

1. In higher latitudes that is near the North pole Tundra climate region is located. It is only on the landmass of Antarctica in the Southern Hemisphere.
2. The countries bordering Arctic Ocean, that is Northern part of North America, Greenland, Eurasia, Antarctic, Peninsula and islands in the polar region are included in this climatic region.
3. This region has also unique climate. There is day light continuously for six months and night for six months.
4. This region has long winters of 10 to 11 months and short summers of 1 to 2 months.
5. This region is away from the equator, so sunrays are slanting, therefore summer temperature is around 10°C, but winters are severe, winter temperature is -20°C to -30°C. Due to low temperature there is low evaporation.
6. There is no rainfall but there is snowfall. Average snowfall is 300 to 500 mm.
7. Polar anticyclones, strong winds, snow storms, coastal fog are common.
8. Due to low temperature hardly moss, lichen grow. In summer when snow melts some flowering plants grow.
9. The main source of livelihood of people is hunting of seals, walrus, polar bear for collection of fur and meat, fishing and mining at some places. Main tribe in this region is Inuits.

Question 3.
Marine West European type climate
Answer:

1. This region as the name suggests is located in the western part of the continent in the latitudinal belt of 45° to 65° N and S.
2. Main countries included in this region are the countries of Western Europe, South Eastern Australia, New Zealand, Western Coastline of USA and Canada, Southern Chile, Southern Alaska.
3. This region has mild to cool summer; average summer temperature is 20°C. Average winter temperature is 5°C. Winters are quite warm due to warm ocean current passing along the coastline.
4. Due to nearness to sea, there is always high cloud cover and high humidity. Average rainfall is 500 to 2500 mm. Fog, frost and drizzle are common.
5. Temperate deciduous trees grow, they shed leaves in winter. Coniferous trees grow on mountain slopes, short green grass grows throughout the year.
6. Fishing, agriculture and animal rearing is the main occupation of the people.

Question 4.
Tropical monsoon climate
Answer:

1. This region extends between 10° and 30° N and S latitudes.
2. This region includes the countries of South East Asia, South West Africa, as well as coastal areas of South West India, North East and South East Brazil, Northern part of Australia and parts of Japan.
3. This region has three distinctive seasons, summer, winter and rainy season, due to seasonal winds called monsoon winds.
4. The summer temperature is 27°C to 32°C, winter temperature is 15°C to 24°C. Annual range of temperature is high.
5. The average rainfall is 250 to 2500 mm. Most of the places receive orographic rainfall. The rainfall is mainly by South West monsoon winds.
6. The climate is controlled by summer onshore and winter offshore wind movements related to shifting of ITCZ.
7. Due to seasonal rainfall, deciduous forest grows, trees shed their leaves in summer. Heavy rainfall areas have equatorial forest, less rainfall areas have thorny vegetation. Herbivores and carnivores live in these forests.
8. Main occupation of people is agriculture due to sufficient temperature, rainfall and fertile soil.

Answer in detail.

Question 1.
Write in brief about China type of climate.
Answer:

1. China type of climate or humid sub-tropical climate is found along East coastal areas between 20° and 40° N and S.
2. The countries of South East USA, South East part of South America, as well as Eastern Australia, South Africa, South china to South Japan and Easter Island in Chile.
3. Summers are mild with temperature 10°C. Winters are cold. The temperature varies between 0°C to 18°C. There is frost in winter.
4. Since these regions are located along the coastline, onshore humid air gives rainfall almost throughout the year. Cyclonic storms are in winter.
5. Due to rainfall throughout the year, there is mixed forest growth. Coniferous forests grow on mountain slopes. Lower slopes of mountains are covered with grass.
6. Agriculture is the main occupation of the people. Main crops grown are rice, wheat, corn, sugarcane, tobacco, cotton, and citrus fruits.

Question 2.
Explain the Highland or Mountain type climate.
Answer:

1. This type of climate is found in all latitudes where there are mountains or highlands.
2. The main areas are mountainous area of Asia, Central Europe, Western North and South America and highlands of Africa.
3. Climate of these regions depend upon the altitude of mountains, highlands, their location on forward and windward slope, their slopes facing the sun etc.
4. In general, mountain/highland region has low temperature since temperature decreases with increase in height.
5. Most of the mountains receive orographic rainfall specially if they are near the coastline. For example, Western Ghats in India receive orographic rainfall by South West monsoon winds.
6. In general, there is snowfall on higher part or slopes of mountains. There is permanent snow cover on the top of mountain. For example, Himalayas are snow covered in their upper part.
7. Generally coniferous forests grow on the upper slopes of mountains that is below snow line. The lower slopes are covered with evergreen or deciduous forests depending on amount of rainfall.
8. Main occupation is animal rearing with the help of pastures on mountain slopes. Due to beautiful scenery of the region tourism is developed in most of the mountainous areas. Agriculture is practiced on terraces slopes.

Balbharti Maharashtra State Board Class 11 Geography Important Questions Chapter 3 Agents of Erosion Important Questions and Answers.

Maharashtra State Board 11th Geography Important Questions Chapter 3 Agents of Erosion

Complete the chain.

Question 1.

Agent	Processes	Erosional / Deposition features
(1) River	(1) Plucking	(1) Hollows
(2) Wind	(2) Solution	(2) Potholes
(3) Glacier	(3) Deflation	(3) Sinkholes
(4) Groundwater	(4) Drilling	(4) Roche moutonnees

Answer:

Agent	Processes	Erosional / Deposition features
(1) River	(1) Drilling	(1) Potholes
(2) Wind	(2) Deflation	(2) Hollows
(3) Glacier	(3) Plucking	(3) Roche moutonnees
(4) Ground water	(4) Solution	(4) Sink holes

Question 2.

Agent	Erosional features	Depositional features
(1) River	(1) Gorge	(1) Moraine
(2) Sea waves	(2) Cirque	(2) Barchan
(3) Wind	(3) Sea cliff	(3) Sand bars
(4) Glaciers	(4) Mushroom rock	(4) Food plains

Answer:

Agent	Erosional features	Depositional features
(1) River	(1) Gorge	(1) Food plains
(2) Sea waves	(2) Sea cliff	(2) Sand bars
(3) Wind	(3) Mushroom rock	(3) Barchan
(4) Glaciers	(4) Cirque	(4) Moraine

Question 3.

Agent	Erosional features	Deposition features
(1) Ground water	(1) Wave cut platforms	(1) Loess
(2) Wind	(2) Horn	(2) Beach
(3) Glacier	(3) Sink holes	(3) Stalactites
(4) Sea waves	(4) Yardang	(4) Eskers

Answer:

Agent	Erosional features	Deposition features
(1) Ground water	(1) Sink holes	(1) Stalactites
(2) Wind	(2) Yardang	(2) Loess
(3) Glacier	(3) Horn	(3) Eskers
(4) Sea waves	(4) Wave cut platforms	(4) Beach

Choose the correct option by identifying the correct correlation in the sentences.

Question 1.
In mountainous areas river flows at a higher speed. Here, …………………
(a) bed gets more eroded than banks
(b) banks get more eroded than bed
(c) both bed and bank get eroded
(d) none of the above
Answer:
(a) bed gets more eroded than banks

Question 2.
The particles of sand are blown away by the wind. After removal the portion from where sand blown off appears as depression. These are called ……………….
(a) Potholes
(b) Barchans
(c) Sand dunes
(d) Deflation hallows
Answer:
(d) Deflation hallows

Question 3.
Landforms developed by underground water anywhere in the world are called ……………….
(a) Deltas
(b) Karst
(c) Aeolian
(d) None of the above
Answer:
(b) Karst

Question 4.
Where two tributary glaciers join together, their lateral moraines merge underneath …………………
(a) to form terminal moraines
(b) to form medial moraines
(c) to form lateral moraines
(d) to form ground moraines
Answer:
(b) to form medial moraines

Question 5.
In this process of transportation, the material acquired by the agents is transported by rolling, pushing and dragging along the surface. The material consists of boulders and big rocks.
(a) Abrasion
(b) Attrition
(c) Traction
(d) Saltation
Answer:
(c) Traction

Question 6.
The process by which moving ice exerts pressure on majority portion of rocks on bed or along the bank is known as ………………..
(a) Abrasion
(b) Plucking
(c) Attrition
(d) Solution
Answer:
(b) Plucking

Question 7.
When rocks and pebbles bump into each other and break up into smaller fragments it is called ………………
(a) Attrition
(b) Abrasion
(c) Drilling
(d) Deflation
Answer:
(a) Attrition

Question 8.
Drumlins are formed by deposition by …………………..
(a) Rivers
(b) Sea waves
(c) Glaciers
(d) Wind
Answer:
(c) Glaciers

Question 9.
Sometimes, waves can erode the softer part and make it hollow enough to be called a ………………..
(a) Cave
(b) Beach
(c) Headland
(d) Sea cliff
Answer:
(a) Cave

Question 10.
………………….. beach at Chennai is the longest beach in India.
(a) Diveagar
(b) Guhagar
(c) Harihareshwar
(d) Marina
Answer:
(d) Marina

Question 11.
The ………………… Lake in Orissa becomes a fresh water lagoon during monsoons.
(a) Dal
(b) Wular
(c) Chilika
(d) Periyar
Answer:
(c) Chilika

Identify the correct correlation.

A : Assertion
R : Reasoning

Question 1.
A – In river beds, gravels and pebbles are often rounded.
R – The rock materials carried in the flow tumble and bounce against one another.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(c) Both A and R are correct and R is the correct explanation of A.

Question 2.
A – The alluvial fans are formed at the foothills.
R – When the river enters the plains, there is change in slope and the velocity of the river increases abruptly.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(a) Only A is correct.

Question 3.
A – Some rivers may not form deltas.
R – They do not have huge load of sediment.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(c) Both A and R are correct and R is the correct explanation of A.

Question 4.
A – Large waves do not get generated in lagoons as they get separated from the sea.
R – The lagoons becomes fresh water lagoon during monsoon.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(d) Both A and R are correct but R is not the correct explanation of A.

Question 5.
A – In arid areas, the eroded portion of softer rocks appear like elongated ridges and harder rocks appear as elevated portions.
R – Softer rocks get more eroded faster.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(c) Both A and R are correct and R is the correct explanation of A.

Identify the incorrect factor.

Question 1.
In the following agent’s abrasion process is used in erosion.
(a) Wind
(b) Sea waves
(c) Glacier
(d) Ground water
Answer:
(d) Ground water

Question 2.
In the following agent’s attrition process is used in erosion,
(a) Ground water
(b) Wind
(c) River
(d) Sea waves
Answer:
(a) Ground water

Question 3.
Solution process of erosion is used in the following agents.
(a) Ground water
(b) Glacier
(c) River
(d) Sea waves
Answer:
(b) Glacier

Question 4.
Lateral erosion process is found in the following agents.
(a) River
(b) Sea waves
(c) Wind
(d) Glacier
Answer:
(c) Wind

Question 5.
Suspension is the process of transportation used by following agents.
(a) Ground water
(b) River
(c) Wind
(d) Sea waves
Answer:
(a) Ground water

Question 6.
Saltation process of transportation is used by following agents.
(a) River
(b) Sea waves
(c) Glacier
(d) Wind
Answer:
(c) Glacier

Question 7.
The erosional landforms of glaciers are.
(a) Cirque
(b) Horn
(c) Moraine
(d) Arete
Answer:
(c) Moraine

Question 8.
The depositional landforms of glaciers are.
(a) Eskers
(b) Drumlin
(c) Erratic rock
(d) Barchan
Answer:
(d) Barchan

Question 9.
The depositional features of ground water are.
(a) Stalactite
(b) Sea stack
(c) Pillar
(d) Stalagmite
Answer:
(b) Sea stack

Question 10.
The erosional features of wind are.
(a) Loess
(b) Ventifacts
(c) Deflation hollows
(d) Yardang
Answer:
(a) Loess

Question 11.
The depositional features of wind are.
(a) Longitudinal dunes
(b) Loess
(c) Barchan
(d) Flood plains
Answer:
(d) Flood plains

Question 12.
The erosional features of sea waves are.
(a) Sea arch
(b) Sea caves
(c) Sink holes
(d) Wave cut platforms
Answer:
(c) Sink holes

Question 13.
The depositional features of sea waves are.
(a) Beaches
(b) Sand bars
(c) Lagoon
(d) Delta
Answer:
(d) Delta

Question 14.
The erosional features of rivers are.
(a) U-Shaped valley
(b) Gorge
(c) Waterfall
(d) Potholes
Answer:
(a) U-Shaped valley

Question 15.
The depositional features of rivers are.
(a) Oxbow lake
(b) Flood plains
(c) Moraines
(d) Meanders
Answer:
(c) Moraines

Complete the table.

Question 1.

Agent	Erosional landforms	Deposition landforms
(1) River	—	—
(2) Wind	—	—
(3) Sea Waves	—	—
(4) Groundwater	—	—
(5) Glacier	—	—

Answer:

Agent	Erosional landforms	Deposition landforms
(1) River	Gorges, V-shaped valleys, canyons, waterfalls, potholes	Alluvial fans, meanders, flood plains, natural levees, deltas
(2) Wind	deflation hollows, ventifacts mushroom rock, yardang	Sand dunes, loess, barchans
(3) Sea Waves	Sea cliffs, cave, sea stack, sea arches, wave cut platform	Beach, sand bar, lagoon, sand pits
(4) Groundwater	Sink holes, caves	Stalactite, stalagmites, pillars
(5) Glacier	Roche mountonnees, cirque, arete, horn, U-shaped valley, hanging valley	Drumlins, eskers, erratic rock, lateral moraines, end moraines, terminal moraines, medial moraines

Question 2.

Agent	Process of erosion	Process of deposition
(1) River	—	—
(2) Wind	—	—
(3) Sea Waves	—	—
(4) Groundwater	—	—
(5) Glacier	—	—

Answer:

Agent	Process of erosion	Process of deposition
(1) River	attrition, solution, drilling, downcutting, headward erosion, lateral erosion	traction, saltation, suspension
(2) Wind	abrasion, attrition, deflation	traction, saltation, suspension
(3) Sea Waves	abrasion, attrition, solution, lateral erosion	traction, saltation, suspension
(4) Groundwater	solution	solution
(5) Glacier	plucking, abrasion, downcutting, headward erosion, lateral erosion	traction

Give geographical reasons.

Question 1.
The coastal zone management warrants serious attention.
Answer:
The coastal zone management warrants serious attention because-

1. Compared to the other agents of erosion the work of sea waves goes on ceaselessly.
2. Erosion in some part and deposition in the adjoining part keeps on taking place constantly. The beaches and bars which are formed due to deposition are also eroded.
3. Coastal regions are always vulnerable to the risk of getting submerged due to increase in sea level.
4. Coastal regions are also the regions of high population density.

Question 2.
Mushroom rocks have broad tops.
Answer:
Mushroom rocks have broad tops because-

1. The high rising rocks in the path of the wind are attacked by the sand that moves with the wind.
2. Winds and the particles they carry, attack the base of an individual rock.
3. The larger top part is not eroded as much as the basal part since, the particles carried by the wind being heavy are not uplifted up to the top portion of the rock.
4. The particles at medium height are smaller but their velocities are high. Hence, their impact is more.
5. As a result, the portion of rock at medium height is eroded more and the rock as a whole gets the shape of a mushroom.

Question 3.
All rivers do not form delta.
Answer:
All rivers do not form delta because –

1. Delta is a place near the seashore where the sediments brough down by a river are deposited in triangular form.
2. Most of the rivers finally join to the sea but every river does not form delta because they do not have the huge load of sediments.
3. If the rivers are travelling from a long distance, they join many tributaries and they deposit the sediment into the main river. Such long and sluggish rivers can deposit sediment at the river mouth and form delta. For example, The River Ganga has formed a huge delta.
4. Some rivers are short and swift. They do not receive more tributaries, so such rivers have less sediments. These rivers flow very swiftly so they deposit sediments in the sea water. Therefore, they do not form delta.

Differentiate between.

Question 1.
Headward erosion and Lateral erosion.
Answer:

Headward erosion	Lateral erosion
(i) Headward erosion is the backward erosion by river in the source region.	(i) Lateral erosion is the erosion that occurs on the sides of valleys of a river or glacier.
(ii) This is carried away by the river.	(ii) The valley slopes are eroded by tributary streams.
(iii) Headward erosion causes the river to move backward, because erosion takes place in the opposite direction of the follow of river.	(iii) Lateral erosion causes widening of valley, because lateral erosion occurs in the valley sides.

Question 2.
Plucking and Abrasion.
Answer:

Plucking	Abrasion
(i) Plucking is the process by which moving ice exerts pressure on rocks on bed or along the bank.	(i) Abrasion involves the scratching and polishing of the surface or bedrock by the particles moving on it.
(ii) The pressure on the rock causes uprooting of rock portion that is exposed to the flow.	(ii) The rock particles involved in abrasion rub against rock and wear away the surface.
(iii) The eroded bedrock will have rugged surface.	(iii) The eroded bedrock will have smooth surface.

Question 3.
Barchan and Longitudinal dunes.
Answer:

Barchan	Longitudinal dunes
(i) When there is an obstacle in the path of wind, or due to low velocity of wind, the sand gets dropped at some places. Thus, barchans are formed.	(i) When sand is deposited parallel to the direction of wind, longitudinal dunes are formed.
(ii) Barchans are crescent-shaped dunes. The slope that faces the wind is gentle whereas the opposite slope is steep.	(ii) They appear parallel to the wind direction. Sometimes they are 100km long.
(iii) Barchans migrate from one place to another.	(iii) Longitudinal dunes do not migrate but extend in the wind direction.
(iv) They are seen in the Great Indian Desert of Rajasthan.	(iv) They are seen in Rub-al-Khali desert of Saudi Arabia.

Write short notes on.

Question 1.
Plucking
Answer:

1. It is the process by which moving ice exerts pressure on majority portion of rocks on bed or along the bank.
2. The pressure on the rock causes uprooting of rock portion that is exposed to the flow. This uprooting of particles is called plucking.
3. The eroded bedrock will have a rugged surface.
4. Plucking at the base of a glacier lead to formation of Roche moutonnees.

Question 2.
Drilling
Answer:

1. Bedload moves along the running water.
2. As and when this flow encounters an obstacle due to relief on the bed or joints in the bed, the flow tends to develop a circular pattern.
3. This circular system becomes stable, though the water continues to flow in downstream direction.
4. This leads to development of a whirl.
5. The trapped sediments also follow the similar circular motion.
6. The continuous action of these trapped sediments and the whirl deepens the bed of the river at a given point.
7. Eventually, it develops into a larger depression assuming a shape of a pot.
8. Potholes are the features formed by this process. For example, they are found in River Indrayani at Bhegadewadi in Pune district.

Question 3.
The Process of deposition
Answer:

1. The velocity at which the agent is moving has a great impact on deposition.
2. If the stream or wind slows down, the carrying capacity and the particle sizes carried and deposited will decrease.
3. If a stream flows faster, say during floods or when the river is in the mountains, then the carrying power of the stream and the sizes of particles deposited will increase.
4. If there is a change in the slope of land or in the direction of flow, deposition may occur there.
5. The slopes are absent in the plain region. Therefore, the rivers are unable to carry the sediments further and they start depositing.
6. Due to gravity, small particles settle more slowly than the larger particles. Smaller particles are carried away by the river or wind till the end and their deposition occurs in the later stage.
7. If an obstacle comes in between the flow of the agent it causes the particles to settle and thus deposition takes place.

Question 4.
Moraine
Answer:

1. Moraine is a depositional feature of a glacier.
2. Glaciers generally deposit load of sediments along the side and front of the ice. These deposits are called moraines.
3. There are four types of moraines depending upon the location where sediments are deposited. They are lateral moraines, medial moraines, terminal moraines and end moraines.
4. The moraines deposited at the sides of the wall are called lateral moraine.
5. When two tributary glaciers join together, their lateral moraines merge underneath to form medial moraines..
6. At the foot of the glacier, sediments are deposited like a heap of all grain sizes forming a curved depositional ridge called end moraines. It contains grains of all sizes.
7. When sediments are deposited at the snout of glacier, when it melts, it is called terminal moraine.

Draw a neat and labelled diagram for.

Question 1.
Yardangs
Answer:

Question 2.
Sea arch
Answer:

Question 3.
Sea stack
Answer:

Question 4.
Pothole drilling
Answer:

Question 5.
Groundwater
Answer:

Answer in detail.

Question 1.
Write in detail about the depositional features formed by glaciers.
Answer:
Following are the depositional features formed by glaciers.
Drumlin:

1. Coarse Material that moves with glaciers gets deposited at different places in the form of heaps.
2. They appear to have egg like shape. Such heaps are called drumlins.
3. At times, large number of drumlins get deposited in an area. From a higher elevation, it- appears like a basket of eggs. It is also referred to as ‘basket of eggs topography’.

Eskers:
When the coarse material, moving with the glaciers is deposited in linear and zigzag manner, it is called an esker.

Erratic rock:

1. In the areas under the influence of glaciers generally at high latitudes, huge rock pieces are found to have been deposited in the area where the local rocks are of different formation.
2. Such rock appears as erratic ones to the area in which they are deposited.
3. These can be considered as guest rocks.

Moraines:

1. Generally, glaciers deposit load of sediments along the side and front of the ice. These deposits are called moraines.
2. The moraines deposited at the sides of the wall are called lateral moraines.
3. At the toe or foot of the glacier, sediment is deposited in a jumbled heap of all grain sizes forming a curved depositional ridge called end moraines.
4. End moraines, that mark the farthest advance of a glacier called terminal moraines.
5. When two tributary glaciers join together, their lateral moraines merge underneath to form medial moraines.

Question 2.
Explain the types of sand dunes.
Answer:
Barchans:

1. These are crescent-shaped dunes.
2. They form where supply of sand is minimum.
3. Due to an obstacle in the path of the wind or due to the lowering of its velocity, the sand moving with it gets dropped at some places.
4. The barchan slope that faces the wind is gentle whereas, the opposite slope is steep.
5. Such barchans are seen in large numbers in the Sahara Desert of Africa or in the Great Indian Desert in Rajasthan.

Longitudinal Dunes:

1. These are long dunes deposited is the direction of the wind.
2. They appear parallel to the wind direction.
3. They do not migrate like the barchans.
4. They are also called seif dunes.
5. They are sometimes hundreds of kilometres long. Such dunes can be seen in Rub-al- Khali desert in Saudi Arabia.

Question 3.
Write about the erosional features formed by river.
Answer:
A river, which is flowing water, erodes rock materials, transports them to newer places and deposits them. In this process, it creates many erosional and depositional landforms. Let us study in details about erosional landforms:

George:

1. In mountainous areas, river flows at a higher speed.
2. Here, the bed gets more eroded than its banks. Gorges are formed with steep banks and a narrow bed. For example, gorges of river Ulhas and river Narmada. Deeper gorges are called canyons.

V-shaped Valleys:

1. Over a period of time, the bed of the river is less eroded.
2. Erosion along the banks and the slope of the valley increases.
3. The vertical sides of the valley become wide resembling letter V’. These are V-shaped valleys.

Waterfalls:
When a river runs over alternating layers of hard and soft rock, rapids and waterfalls are formed. Jog falls on the Sharavati river.

Potholes:

1. They generally originate below waterfalls on where rocks are structurally weak.
2. Swirling whirlpool motions of the river water causes stones at the bottom to grind the bedrock and enlarge the potholes by drilling while finer sediments are carried away in the current.
3. Potholes may range from a few centimetres to many meters in diameter and depth. For example, large potholes can be seen in the beds of river Kukadi at Nighoj in Ahmednagar district.

Balbharti Maharashtra State Board Class 11 Geography Important Questions Chapter 2 Weathering and Mass Wasting Important Questions and Answers.

Maharashtra State Board 11th Geography Important Questions Chapter 2 Weathering and Mass Wasting

Complete the chain

Question 1.

Types of Mass	Wasting Characteristics	Regions
(1) Creep	(1) Rapid fall	(1) Periglacial or alpine region
(2) Rockfall	(2) Slowest moving	(2) Hillsides in a humid region
(3) Earth flow	(3) Slow downhill creep	(3) Rocky areas
(4) Solifluction	(4) Rapid or slow	(4) Tops and basal portions of hills

Answer:

Types of Mass	Wasting Characteristics	Regions
(1) Creep	(1) Slowest moving	(1) Tops and basal portions of hills
(2) Rock fall	(2) Rapid fall	(2) Rocky areas
(3) Earth flow	(3) Rapid or slow	(3) Hill sides in humid region
(4) Solifluction	(4) Slow downhill creep	(4) Periglacial or alpine region

Question 2.

Types of weathering	Factors	Resultant
(1) Physical	(1) Heat	(1) Oxidation
(2) Chemical	(2) Explosion	(2) Granular weathering
(3) Anthropological	(3) Water (H2O)	(3) Exfoliation
	(4) Pressure	(4) Mining

Answer:

Types of weathering	Factors	Resultant
(1) Physical	(1) Heat Pressure	(1) Exfoliation, Granular weathering
(2) Chemical	(2) Water (H2O)	(2) Oxidation
(3) Anthropological	(3) Explosion	(3) Mining

Choose the correct option by identifying the correct correlation in the sentences.

Question 1.
Rocks can break because of …………….
(a) water, pressure, heat, etc.
(b) gravity
(c) deposition
(d) sedimentation
Answer:
(a) water, pressure, heat, etc.

Question 2.
In rocks such as granite which have joints, heat can cause weathering ………………….
(a) by breaking the rock into two halves
(b) by breaking the rock along the joints into blocks
(c) by breaking the rock into pieces
(d) by shattering
Answer:
(b) by breaking the rock along the joints into blocks

Question 3.
Chemical weathering is effective and rapid in …………………
(a) cold climate
(b) hot climate
(c) humid climate
(d) dry climate
Answer:
(c) humid climate

Question 4.
Erosion involves the application of ………………
(a) kinetic energy to the surface along which the material moves
(b) gravitational force to the surface along which the material moves
(c) tensional force to the surface along which the material moves
(d) compressional force to the surface along which the material moves
Answer:
(a) kinetic energy to the surface along which the material moves

Question 5.
The salts of calcium, sodium etc., present in rocks have a tendency to expand, this leads to ………………..
(a) breaking of rocks
(b) dissolving the salts
(c) formation of cracks in rocks
(d) crystallization of salts
Answer:
(d) crystallization of salts

Question 6.
Water molecules react with minerals present in the rocks. This process is called ………………..
(a) solution
(b) hydrolysis
(c) oxidation
(d) carbonation
Answer:
(b) hydrolysis

Question 7.
The calcium present in ………………. reacts with the water and air to form carbonic acid.
(a) limestone
(b) marble
(c) granite
(d) slate
Answer:
(a) limestone

Question 8.
During ………………., the calcium and carbonate in limestone detach from each other, thereby decomposing the limestone.
(a) oxidation
(b) solution
(c) desilication
(d) carbonation
Answer:
(d) carbonation

Question 9.
When rocks break along joints due to heat, it is called ……………….
(a) block disintegration
(b) cracks
(c) shattering
(d) granular weathering
Answer:
(a) block disintegration

Question 10.
Mining, blasting of hills and ridges is a type of …………….. weathering.
(a) physical
(b) chemical
(c) biological
(d) anthropogenic
Answer:
(d) anthropogenic

Question 11.
Mass movements occur continuously on all …………………
(a) plains
(b) plateau
(c) slopes
(d) rivers
Answer:
(c) slopes

Question 12.
The ……………….. plays a big role in stabilizing slopes.
(a) gravity
(b) water
(c) slope
(d) vegetation
Answer:
(d) vegetation

Question 13.
Slow downhill creep of soil in periglacial or alpine regions is known as ………………..
(a) rock fall
(b) solifluction
(c) earth flow
(d) landslide
Answer:
(b) solifluction

Identify the correct correlation

Question 1.
A – Mass wasting is effective on slopes that are made up of clay and shale.
R – Mass wasting determines the material of the slope.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(c) Both A and R are correct and R is the correct explanation of A.

Question 2.
A – Microscopic organisms like algae, moss, lichens cause biological weathering.
R – They produce chemicals on the outer layer of the rocks.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(c) Both A and R are correct and R is the correct explanation of A.

Question 3.
A – Quartzite, a metamorphic rock, is harder than steel.
R – It does not easily react physically but is easily fractured by chemical weathering.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(d) Both A and R are correct but R is not the correct explanation of A..

Question 4.
A – In mass movements, the materials come down the slope without the aid of a transporting medium like running water, ice or wind.
R – Anthropogenic weathering is responsible for mass movement.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(a) Only A is correct

Question 5.
A – Steeper slope will also have higher possibility of slow mass movement.
R – Gentle slopes will have slow mass movement.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(b) Only R is correct.

Question 6.
A – Mass movement is based on how quickly the rock and weathered material moves due to friction, gravity, load of material.
R – The rock and material move because of running water.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(d) Both A and R are correct but R is not the correct explanation of A.

Identify the incorrect factor.

Question 1.
The factors that affect mechanical weathering.
(a) Water
(b) Heat
(c) Pressure
(d) Microscopic organism
Answer:
(d) Microscopic organism

Question 2.
The factors that affect biological weathering.
(a) Mining
(b) Microscopic organism
(c) Barrowing animals
(d) Roots of trees
Answer:
(a) Mining

Question 3.
The reasons for anthropogenic weathering.
(a) Mining
(b) Pressure
(c) Road construction
(d) Quarrying for building material
Answer:
(b) Pressure

Question 4.
The factors responsible for mass movements.
(a) Gravity
(b) Water
(c) Heat
(d) Relief and slope
Answer:
(c) Heat

Question 5.
The mass movements can be divided into four main classes.
(a) Creep
(b) Fall or topple
(c) Flows
(d) Weak material and structure
Answer:
(d) Weak material and structure

Question 6.
The types of mass wasting.
(a) Fall or topple
(b) Landslide
(c) Solifluction
(d) Rock fall
Answer:
(a) Fall or topple

Identify the correct group

Question 1.

A	B	C	D
(1) Algae	(1) Rock fall	(1) Relief and slope	(1) Shattering
(2) Roots and plants	(2) Landslide	(2) Gravity	(2) Block disintegration
(3) Lichens	(3) Earth flow	(3) Water	(3) Exfoliation
(4) Moss	(4) Exfoliation	(4) Vegetation	(4) Burrowing

Answer:
A

Give geographical reasons

Question 1.
Many times, rocks break.
Answer:
Rocks break because-

1. Rocks which are exposed are affected by the climate of that region in various ways.
2. Rocks can break because of water, pressure, heat, etc. in various ways.
3. Those rocks which have joints or layers, break easily than rocks which are homogeneous.
4. The rocks which have vertical strata are easily loosened and break, due to changes in temperature, water, wind or frost action.
5. If there are larger grains in the rocks, there is ample space in the rocks for water to enter and they get weathered easily and break.
6. Some rocks are very hard and resistant to chemical weathering but they are easily fractured by physical weathering.
7. Generally, sedimentary rocks break easily than igneous rocks and metamorphic rocks.

Question 2.
Water plays an important role in weathering.
Answer:
Water plays an important role in weathering because-

1. In areas where diurnal range of temperature is high, water inside the crack’s freezes. During daytime, it again becomes water.
2. When water freezes, its volume increases due to the pressure exerted on the walls of the rock, the cracks in the rocks widen and finally rock breaks down due to freeze and thaw weathering.
3. Water also breaks down the rocks chemically. The water molecules react with minerals present in the rocks. This is called hydrolysis.
4. Another way by which water can cause chemical weathering is by solution. Minerals like calcium, magnesium dissolves in water.
5. Oxygen present in air and water reacts with iron or aluminium present in rock and as a result rock rusts and ultimately breaks.

Question 3.
Biological weathering is the disintegration of rocks as a result of action by living organisms.
Answer:
Biological weathering is the disintegration of rocks as a result of action by living organisms because-

1. Roots of trees and other plants penetrate into the soil and grow in size. Thus, they exert pressure on rocks and make the cracks wider and deeper.
2. Some plants grow within fissures and lead to disintegration.
3. Microscopic organisms such as algae, moss, lichens and bacteria grow on rock surface and produce chemicals, they react on outer layers the rocks and break them.
4. Man known for his economic and technological development becomes the most powerful weathering and erosion agent. Mining, blasting, construction of roads, railways etc., result in fast disintegration of rocks.
5. There are some barrowing animals like rats, when they barrow, rocks are broken.

Question 4.
Vegetation plays a big role in stabilizing slopes.
Answer:
Vegetation plays a big role in stabilizing slopes because-

1. The strong root system of trees and other plants help to hold the soil in place.
2. When these trees are removed, the soil becomes loose and can be easily washed away.
3. This is why, when there is dense forest cover there is stabilization of slopes but deforested areas are likely to be sites of mass wasting.

Differentiate between.

Question 1.
Physical weathering ad Chemical weathering.
Answer:

Physical weathering	Chemical weathering
(i) Physical weathering may be defined as the disintegration or breaking of rocks without changing the properties of the rock.	(i) Chemical weathering is the process by which the internal structures of a mineral is altered by the addition or renewal of elements.
(ii) This type of weathering occurs mainly by temperature and pressure changes.	(ii) This type of weathering occurs when water activates several types of chemical reactions within the rocks.
(iii) In general, cold dry climate accelerates physical weathering.	(iii) Hot wet climate accelerates chemical weathering.
(iv) E.g. Exfoliation	(iv) E.g. Oxidation

Question 2.
Landslides and Earth flow.
Answer:

Landslides	Earth flow
(i) All types of mass movements of rock, debris, including soils and ice are collectively called landslides.	(i) Diagonal down slope movement of rock fragments and fine-grained material along sliding plane with enough water is called earth flow.
(ii) Landslides occur on steep or gentle slope gradient, from mountain range to coastal cliffs.	(ii) Earth flow is more common or hillsides or valley sides having rich minerals.
(iii) Gravity is primary force for the landslide to occur, others are slope stability, heavy rainfall or earthquake.	(iii) The primary reason for Earth flow is continuous heavy rainfall which saturates the ground and increases the pour water pressure, and earth flow starts.

Question 3.
Rockfall and Solifluction.
Answer:

Rockfall	Solifluction
(i) Rapid fall of rock material down or rock travel downwards bouncing and rolling is termed as rock fall.	(i) Solifluction is the name for the slow downhill creep of soil.
(ii) Rockfalls occur mainly in rocky areas.	(ii) Solifluction occurs mainly in periglacial or alpine regions.
(iii) The size of rockfall blocks can range from one cubic centimetre to ten thousand cubic meters.	(iii) The size of material in solifluction is very small since it contains particles of soil.

Write short notes on

Question 1.
Types of Mass Wasting
Answer:
Mass wasting or mass movement is the down slope movement of loose mixture of soil, land and rock particles by force of gravity.
Following are different types of mass wasting:
Creep:

1. Very slow imperceptible down slope movement of materials is called creep.
2. It occurs along top and basal portions of hills.

Rock fall:

1. Rock falls are relatively small landslides confined to the removal of individual and superficial blocks down a cliff base.
2. It mainly occurs in rocky areas.

Earth flow:

1. Earth flow is promoted by excessive water received mostly through rainfall so that the materials are oversaturated.
2. It typically occurs on hill sides in humid regions.

Solifluction:

1. Solifluction is the name for the slow downhill creep of soil, which occurs in a variety of climatic conditions.
2. It occurs in periglacial or alpine regions.
3. It occurs very slowly, so it is measured in millimetres or centimetres.
4. As permafrost is impermeable to water, soil overlying may become oversaturated and the slides slope down under the pull of gravity.

Landslide:

1. It may be mentioned that generally all types of mass movements of rock wastes including soils and ice are collectively called landslides.
2. It occurs on moderately steep slopes.
3. Gravity is primary force for the landslide to occur, others are slope stability, heavy rainfall or earthquake.

Question 2.
Biological Weathering:
Answer:
Flora : Roots of trees penetrate into the soil in search of minerals. Sometimes the plants grow within the fissures in the rock leading to widening of the fissures and eventually rocks disintegrate.

Fauna : Microscopic organisms such as algae, moss, lichens and bacteria grow on rock surface and produce chemicals, which react with the rock surface and create weathering. Burrowing animals like moles, mice, rats, reptiles, like snakes etc., dig holes in the soil and speed up disintegration.

Draw a neat diagram and labelled for:

Question 1.
Exfoliation
Answer:

Answer in Details

Question 1.
Explain different types of mass wasting.
Answer:
Mass wasting is the down slope movement of loose mixture of soil, land and rock particles by force of gravity.
Following are different types of mass wasting:

Creep:

1. Very slow imperceptible down slope movements of materials is called creep.
2. It occurs along tops and basal portions of hills.

Rock fall:

1. Rock falls are relatively small landslides confined to the removal of individual and superficial blocks from cliff base.
2. It mainly occurs in rocky areas.

Earth flow:

1. Earth flow is promoted by excessive water received mostly through rainfall so that the materials are oversaturated.
2. It typically occurs on hill slides in humid regions.

Solifluction:

1. Solifluction is the name for the slow downhill creep of soil, which occurs in variety of climatic conditions.
2. It occurs in periglacial or alpine regions.
3. As permafrost is impermeable to water, soil overlying may become oversaturated and slide slope down under the pull of gravity.

Landslide:

1. It may be mentioned that generally all types of mass movements of rock wastes including soils and ice are collectively called landslides.
2. It occurs on moderately steep slopes.

Question 2.
What is weathering? Explain different types of weathering.
Answer:
Weathering refers to the break down or disintegration and decomposition of rocks in situ through mechanical and chemical changes in the rocks and their minerals affected by water temperature, wind, different atmospheric gases and organisms. Following are the types of weathering-

Let us study the types in details:
Physical Weathering:
(i) Water:

1. In areas where diurnal temperature range is high, water inside the crack’s freezes during night and melts during daytime.
2. Due to this continuous freezing and thawing, the cracks widen and disintegration of rocks takes place. This is called freeze and thaw weathering.

(ii) Heat:

1. In hot deserts the temperature increases during the day. The minerals present in the rock react differently to the increased temperature.
2. The minerals within the rock expand leading to stress and the rock breaks into individual mineral grains. This is called as granular disintegration.
3. In the similar process, in the deserts during day time the rock surface gets heated and shatters. It may produce a breaking sound. This is called shattering.
4. In rocks such as granite which have joints, heat can cause weathering by breaking the rocks along the joints into blocks. This is called block disintegration.

Pressure:

1. Due to overlying rocks, the rocks beneath the surface experience a lot of pressure.
2. When the underlying rock gets exposed to the surface, they are subjected to low pressure. As a result of pressure differences, the rock mass expands outwards.
3. The expansion causes outer layer to separate from lower layer. It is called dislodgement which happens due to pressure release. It is mainly observed in igneous rocks which are more homogeneous. The continuous removal of outer layer of the rock is called exfoliation.

Chemical Weathering:

1. Oxidation: When oxygen from air and water reacts with iron or bauxite present in the rocks, iron and aluminium oxides are formed. The colour of the rock changes and it is called rusting.
2. Carbonation: When carbon-dioxide reacts with the minerals in the soil, carbonation takes place. The decomposition of dead produces C02, which reacts with minerals in the rocks.
3. Solution: When some minerals in the rocks reacts with water in the rock or moisture in the air and gets dissolved, it is called solution. For example, chalk dissolves in water.
4. Salt: The salts of calcium, sodium, magnesium, potassium etc., present in the rocks have a tendency to expand due to their thermal properties. This leads to crystallization of salts and individual grains spilt from main rocks and fall off at the end.

Biological Weathering:
Flora : Roots of trees penetrate into the soil in search of minerals. Sometimes the plants grow within the fissures in the rock leading to widening of the fissures and eventually disintegrating.

Fauna : Microscopic organisms such as algae, moss, lichens and bacteria grow on rock surface and produce chemicals, which react with the rock surface and create weathering. Burrowing animals like moles, mice, rats, reptiles, like snakes etc., dig holes in the soil and speeds up disintegration.

Anthropogenic weathering:
Man is responsible for weathering as he constructs roads, railways, do mining etc.

1. Man being a biological agent affects weathering.
2. With economic and technological development, man has become the most powerful weathering and erosion agent.
3. Mining, blasting of hills and ridges for road and dam construction, quarrying for industrial and building materials, etc result in a fast rate of disintegration of rocks.
4. This may be accomplished by natural weathering processes in thousands to millions of years.
5. Man accelerates the rate of weathering on hill slopes through activities like deforestation.

Question 3.
Classify and explain mass movement on basis of weathered material.
Answer:

1. Fall or topple: It happens when rocks have a free fall and land at the bottom of a slope.
2. Flows: A mixture of water, rock and weathered material. They move very quickly. Large flows can bury an entire village. Small flows can block roads.
3. Slide: A slide happens when section of soil or rock suddenly gives way and moves down a slope. The material moves as a single mass along a slippery zone.
4. Creep: It is a very slow mass movement that goes on for years or even centuries.

Question 4.
What are the factors affecting mass movement?
Answer:
The factors responsible for mass movement are:
Relief and slope:

1. There should be considerable elevation in an area for down slope movement to occur.
2. Such movements will not occur in plain areas.
3. Hilly, mountainous and plateau areas are more vulnerable to such movements.
4. The steeper the slope, higher are the chances of occurrence of mass movements. Gentle slopes will have slow movements while steep slopes will have rapid movements.

Gravity:

1. It is the main force responsible for mass movements.
2. It is a force that acts everywhere on the surface of the earth, pulling everything down.

Water:

1. Although water is not always directly involved as transporting medium but it plays an important role.
2. Addition of water from rainfall or snowfall or melting of snow makes the material on the slope heavier.
3. Water can reduce the friction along a sliding surface.

Weak material and structures:

1. Some rocks are weaker than others. Rocks which have joints break easily.
2. In particular, rocks containing calcium or clay minerals tend to have a low strength.
3. Such areas will be more susceptible to mass wasting.

Question 5.
Complete the following flow chart.

Answer:

Balbharti Maharashtra State Board 12th Biology Important Questions Chapter 5 Origin and Evolution of Life Important Questions and Answers.

Maharashtra State Board 12th Biology Important Questions Chapter 5 Origin and Evolution of Life

Multiple Choice Questions

Question 1.
Which statement is true for the theory of spontaneous generation?
(a) Life came from outer space.
(b) Life can arise from dead matter.
(c) Life can arise from non-living things only
(d) Life arises spontaneously by miracle
Answer:
(c) Life can arise from non-living things only

Question 2.
When man makes the selection during animal husbandry and plant breeding programmes, then it is an example of ……………….
(a) reverse evolution
(b) artificial selection
(c) mutation
(d) natural selection
Answer:
(b) artificial selection

Question 3.
Palaeontological evidences for evolution are ……………….
obtained in the form of
(a) development of embryo
(b) homologous organs
(c) fossils
(d) analogous organs
Answer:
(c) fossils

Question 4.
The homologous organs such as bones of forelimbs of whale, bat, cheetah and man are similar in structure, because ……………….
(a) one organism has given rise to another
(b) they share a common ancestor
(c) they perform the same function
(d) they have biochemical similarities
Answer:
(b) they share a common ancestor

Question 5.
Which type of evolution gives rise to analogous organs?
(a) divergent evolution
(b) parallel evolution
(c) genetic drift
(d) convergent evolution
Answer:
(d) convergent evolution

Question 6.
Hardy Weinberg’s equation of genetic equilibrium i.e. (p + q)² = p² + 2pq + q² = 1 is used in ……………….
(a) population genetics
(b) Mendelian genetics
(c) biometrics
(d) molecular genetics
Answer:
(a) population genetics

Question 7.
Which type of rocks show maximum fossils ?
(a) Sedimentary rocks
(b) Igneous rocks
(c) Metamorphic rocks
(d) Any type of rock
Answer:
(a) Sedimentary rocks

Question 8.
Industrial melanism observed in moth, Biston bitularia shows ………………. type of natural selection.
(a) stabilising
(b) directional
(c) disruptive
(d) artificial
Answer:
(b) directional

Question 9.
Variations during mutations of meiotic recombinations are ……………….
(a) random and directionless
(b) random and directional
(c) small and directional
(d) random, small and directional
Answer:
(a) random and directionless

Question 10.
Theory of special creation is based on ………………. beliefs.
(a) scientific
(b) religious
(c) traditional
(d) mythological
Answer:
(b) religious

Question 11.
Which sentence holds true for theory of biogenesis?
(a) Living organisms arise from non-living things.
(b) Theory of biogenesis can explain origin of life.
(c) Continuity of life can be explained by this theory.
(d) This theory was disproved by Louis Pasteur.
Answer:
(c) Continuity of life can be explained by this theory

Question 12.
Who gave the Big-Bang theory that explained the origin of life ?
(a) Georges Lemaitre
(b) Oparin and Haldane
(c) Charles Darwin
(d) J.B.S. Haldane
Answer:
(a) Georges Lemaitre

Question 13.
Primitive atmosphere of the earth was of type ……………….
la) oxidizing
(b) reducing
(c) aerobic
(d) oxido-reducing
Answer:
(b) reducing

Question 14.
What is the meaning of protobiogenesis?
(a) The origin of life on the earth.
(b) The origin of protozoans on the earth.
(c) The origin of protists on the earth.
(d) The origin of protons of the earth.
Answer:
(a) The origin of life on the earth

Question 15.
What are the first form of life on the earth called ?
(a) Pre-cells or Protobionts
(b) Protoproteins
(c) Coacervates
(d) Chromophores
Answer:
(a) Pre-cells or Protobionts

Question 16.
Which of the following is a landmark in the origin of life ?
(a) Formation of oxygen
(b) Formation of carbohydrates
(c) Formation of proteins
(d) Formation of water
Answer:
(c) Formation of proteins

Question 17.
The first chemicals formed on the earth were ………………. etc.
(a) oxygen, CFC, ozone
(b) DNA. RNA and nucleotides
(c) salt, sugar, proteins
(d) water, ammonia, methane
Answer:
(d) water, ammonia, methane

Question 18.
The unique feature of hot dilute soup is that there was no free ………………. in it.
(a) nitrogen
(b) oxygen
(c) carbon
(d) sulphur
Answer:
(b) oxygen

Question 19.
On which plant did Hugo de Vries work during his experimentations?
(a) Hibiscus rosa sinensis
(b) Oenothera lamarkiana
(c) Mirabilis jalapa
(d) Pisum sativum
Answer:
(b) Oenothera lamarkiana

Question 20.
Which one out of the following is a connecting link between fish and amphibian ?
(a) Archaeopteryx
(b) Seymouria
(c) Ichthyostega
(d) Dinosaurus
Answer:
(c) Ichthyostega

Question 21.
Homologous organs always lead to ………………. evolution.
(a) convergent
(b) divergent
(c) parallel
(d) radiating
Answer:
(b) divergent

Question 22.
Find the odd one out
(a) Caecum
(b) Nictitating membrane
(c) Coccyx
(d) Sacrum
Answer:
(d) Sacrum

Question 23.
The most common types of fossils are ……………….
(a) moulds
(b) casts
(c) actual remains
(d) model
Answer:
(c) actual remains

Question 24.
In geological time scale which period showed dominance of reptiles ?
(a) Triassic
(b) Jurassic
(c) Cretaceous
(d) Eocene
Answer:
(b) Jurassic

Question 25.
Which was the period of beginning of modern birds ?
(a) Triassic
(b) Jurassic
(c) Cretaceous
(d) Eocene
Answer:
(c) Cretaceous

Question 26.
Which epoch showed mammals at height of evolution ?
(a) Eocene
(b) Oligocene
(c) Miocene
(d) Pliocene
Answer:
(c) Mlocene

Question 27.
When did Holocene began ? (mya = million years ago)
(a) 2 mya
(b) 1 mya
(c) 0.5 mya
(d) 0.01 mya
Answer:
(d) 0.01 mya

Question 28.
Cichlid fishes in Lake Victoria are representatives of ………………. type of speciation.
(a) allopatric
(b) sympatric
(c) isolation
(d) random
Answer:
(b) sympatric

Question 29.
Which is the offspring of male horse and female donkey?
(a) Mule
(b) Hinny
(c) Marino
(d) Baroque
Answer:
(b) Hinny

Question 30.
Which one out of the following is a living fossil ?
(a) Coelacanth
(b) Lung fish
(c) Shark
(d) Rays
Answer:
(a) Coelacanth

Question 31.
Giant cephalopods like Nautilus were present in ………………. period.
(a) Silurian
(b) Devonian
(c) Ordovician
(d) Permian
Answer:
(c) Ordovician

Question 32.
First modern birds were formed during ………………. period.
(a) Triassic
(b) Jurassic
(c) Cretaceous
(d) Eocene
Answer:
(c) Cretaceous

Question 33.
When did man emerge during evolutionary time period ?
(a) Eocene
(b) Oligocene
(c) Miocene
(d) Pliocene
Answer:
(d) Pliocene

Question 34.
Find the odd monkey out:
(a) Baboons
(b) Gibbons
(c) Macaques
(d) Langurs
Answer:
(b) Gibbons

Question 35.
Who was man with ape-brain ?
(a) Pithecanthropus
(b) Dryopithecus
(c) Australopithecus
(d) Neanderthal man
Answer:
(c) Australopithecus

Question 36.
Who was the first true man ?
(a) Pithecanthropus
(b) Cro-magnon
(c) Australopithecus
(d) Neanderthal man
Answer:
(a) Pithecanthropus

Question 37.
Which one of the following is not present in human beings ?
(a) S curves in vertebral column
(b) Orthognathus face
(c) Simian gap
(d) Chin
Answer:
(c) Simian gap

Question 38.
Which is the correct sequence of human evolution ?
(a) Australopithecus → Ramapithecus → Homo sapiens → Homo habilis
(b) Homo erectus → Homo habilis → Homo sapiens
(c) Ramapithecus → Homo habilis → Homo erectus → Homo sapiens
(d) Australopithecus → Ramapithecus → Homo erectus → Homo habilis → Homo sapiens.
Answer:
(c) Ramapithecus – Homo hablUs -‘ Homo erectus Homo sapiens

Question 39.
Fossils of Homo erectus were obtained in ………………. and ……………….
(a) Kenya, Shivalik hills
(b) Java, Peking
(c) Africa, Asia
(d) Neanderthal valley, Taung
Answer:
(b) Java, Peking

Question 40.
Dentition more like that of the modern man was seen for the first time in ……………….
(a) Dryopithecus
(b) Ramapithecus
(c) Australopithecus
(d) Homo habilis
Answer:
(d) Homo habilis

Question 41.
Lemur and Tarsier belongs to ……………….
(a) Prosimi
(b) Hyalobatidae
(c) Pongidae
(d) Homonidae
Answer:
(a) Prosimi

Match the columns

Question 1.

Geological time	Animal life
(1) Cambrian	(a) Amphibians
(2) Ordovician	(b) First terrestrial animals
(3) Silurian	(c) Jawless fishes
(4) Devonian	(d) Trilobite

Answer:

Geological time	Animal life
(1) Cambrian	(d) Trilobite
(2) Ordovician	(c) Jawless fishes
(3) Silurian	(b) First terrestrial animals
(4) Devonian	(a) Amphibians

Question 2.

Human stage	Cranial capacity in CC
(1) Homo sapiens	(a) 650-800
(2) Homo neanderthalensis	(b) 900
(3) Homo habilis	(c) 1400
(4) Homo erectus	(d) 1450

Answer:

Human stage	Cranial capacity in CC
(1) Homo sapiens	(d) 1450
(2) Homo neanderthalensis	(c) 1400
(3) Homo habilis	(a) 650-800
(4) Homo erectus	(b) 900

Classify the following to form Column B as per the category given in Column A

Question 1.
Nictitating membrane, Seymouria, Lung fish, Flipper of whale and wing of bird, Wing of insect and wing of bird, wisdom
tooth, Eye of octopus, an eye of mammal, vertebrate heart and brain.

Column I	Column II
(1) Homologous organs	————-
(2) Analogous organs	————-
(3) Vestigial organs	————-
(4) Connecting links	————-

Answer:

Column I	Column II
(1) Homologous organs	Flipper of whale and wing of bird, Vertebrate heart and brain
(2) Analogous organs	Wing of insect and wing of bird. Eye of octopus, an eye of mammal
(3) Vestigial organs	Nictitating membrane, wisdom tooth
(4) Connecting links	Seymouria, Lung fish

Question 2.
Origin of conifers, Abundance of trilobites, Diversification of fishes, All types of marine algae, Formation of forests, Rise of dinosaurs, Extinction

Geological time period	Major events
Cambrian	————-
Devonian	————-
Permian	————-
Triassic	————-

Answer:

Geological time period	Major events
Cambrian	Abundance of trilobites, All types of marine algae
Devonian	Diversification of fishes, Formation of forests
Permian	Origin of conifers. Rise of modern insects.
Triassic	Rise of dinosaurs, Extinction of seed ferns

Very short answer questions

Question 1.
What is protobiogenesis?
Answer:
The origin of life on the earth is called protobiogenesis.

Question 2.
What are panspermia?
Answer:
Panspermia or cosmozoa are considered to be spores through which life came on the earth from distant planets.

Question 3.
What are protobionts?
Answer:
Protobionts were first form of life which were formed by nucleic acids along with other inorganic and organic molecules. They have some properties of living form.

Question 4.
What are eobionts?
Answer:
Eobionts or protocells are the first primitive living system which are formed by colloidal aggregations of lipids and proteinoids.

Question 5.
When did universe originate? How?
Answer:
Universe originated about 20 billion years ago by huge titanic explosion called big- bang.

Question 6.
What were the different energy sources during primitive times when earth was cooling?
Answer:
The different available energy sources during primitive times were ultra-violet rays, radiations, lightning and volcanic activities.

Question 7.
How was first cell formed on the primitive earth?
Answer:
In the protocell, when RNA or DNA system developed and they started regulating various metabolic activities, then it was called a first cell.

Question 8.
How was first cell formed on the primitive earth?
Answer:
In the protocell, when RNA or DNA system developed and they started regulating various metabolic activities, then it was called a first cell.

Question 9.
How was first cell on the earth in its metabolism ?
Answer:
First cell was anaerobic, heterotrophic and obtained energy by chemoheterotrophic processes.

Question 10.
What are ribozymes?
Answer:
Ribozymes are catalytic RNA which act as biocatalyst.

Question 11.
Who disproved Lamarck’s theory?
Answer:
August Weismann disproved Lamarck’s theory.

Question 12.
Write theory of germplasm as suggested by Wallace.
Answer:
The theory of germplasm says that variations produced in germ cells or germplasm are inherited to next generations, but the somatic variations present in somatoplasm or somatic cells are not inherited.

Question 13.
Who are the main contributors of modem : synthetic theory of evolution?
Answer:
R. Fischer, J. B. S. Haldane, T. Dobzhansky, Huxley, E. Mayr, Simpson, Stebbins, Fisher, Sewall Wright, Medel, T. H. Morgan, etc. are the main contributors of modern theory of evolution.

Question 14.
What is variation?
Answer:
The variations are the differences that occur in morphology, physiology, nutrition, habit, behavioural patterns, etc.

Question 15.
What is mutation?
Answer:
Sudden, large, inheritable and drastic change occurring in the genetic constitution is called mutation.

Question 16.
What is gene frequency?
Answer:
Gene frequency is the relative frequency of an allele or a gene at a particular locus in a population, as compared to other genes, expressed as a fraction or percentage.

Question 17.
What is the other name for genetic drift?
Answer:
Sewall wright effect is the other name for genetic drift.

Question 18.
Why is genetic drift called founder’s effect?
Answer:
The allelic frequency of new population which undergoes genetic drift becomes different from the original one, thus the original drifted population becomes different and are called ‘founders’. Since founders are formed therefore genetic drift is called founder’s effect.

Question 19.
What are fossils?
Answer:
Fossils are the dead remains of plants and animals from prehistoric times, which are found in different forms such as moulds, casts, actual remains or compression seen in various geological layers.

Question 20.
What is embryology?
Answer:
Embryology is the branch of biology and medicine which deals with study of embryos and their development.

Give definition of the following

Question 1.
Gene flow
Answer:
The transfer of genes between two genetically different populations among themselves is called gene flow.

Question 2.
Genetic drift
Answer:
Any random fluctuation (alteration) in allele frequency, occurring in the natural population by pure chance, is called genetic drift.

Question 3.
Chromosomal aberrations
Answer:
The structural, morphological change in chromosome due to rearrangement, is called chromosomal aberrations.

Question 4.
Mendelian population
Answer:
Small interbreeding group of a population is defined as Mendelian population.

Question 5.
Crossing over
Answer:
Exchange of genetic material between non-sister chromatids of homologous chromosomes in sexually reproducing organisms, during gamete formation is called crossing over.

Question 6.
Saltation
Answer:
Saltation is defined as single step large mutation.

Name the following

Question 1.
The book written by Charles Darwin after returning from voyage.
Answer:
Origin of species by natural selection.

Question 2.
Five main postulates of Darwinism.
Answer:

1. Overproduction
2. Struggle for existence
3. Organic variations
4. Natural selection
5. Origin of next species.

Question 3.
Five key factors of evolution as suggested by Stebbins.
Answer:

1. Gene mutations
2. Mutations in the chromosome structure and number
3. Genetic recombinations
4. Natural selection
5. Reproductive isolation.

Question 4.
Name the four types of chromosomal aberrations.
Answer:

1. Deletion
2. Translocation
3. Duplication
4. Inversion

Question 5.
Name of the insect that displayed industrial melanism and the name of the scientist who studied them.
Answer:
Kettlewell reported that Biston betularia or peppered moth displayed industrial melanism.

Question 6.
Example of homologous organs in plants.
Answer:
Thorns of Bougainvillea and tendrils of Cucurbita.

Question 7.
Example of analogous organs in plants.
Answer:
Sweet potato and potato.

Question 8.
Pre-mating isolating mechanisms.
Answer:

1. Habitat or ecological isolating mechanism
2. Seasonal or temporal isolating mechanism
3. Ethological isolating mechanism
4. Mechanical isolating mechanism

Question 9.
Post-mating isolating mechanisms.
Answer:

1. Gamete mortality
2. Zygote mortality
3. Hybrid sterility

Question 10.
Name of connecting link between reptiles and birds.
Answer:
Archaeopteryx is the connecting link between reptiles and birds.

Question 11.
Name of connecting link between amphibians and reptiles.
Answer:
Seymouria is the connecting link between amphibians and reptiles.

Question 12.
Name of connecting link between fish and amphibians.
Answer:
Ichthyostegia is a missing link between fish and amphibians.

Question 13.
Name the period that was dominant for Amphibia.
Answer:
Carboniferous is dominant period for Amphibia.

Question 14.
Name the epoch when mammals were at the height of evolution.
Answer:
Miocene epoch.

Question 15.
Name the era when birds began to origin.
Answer:
Mesozoic era.

Question 16.
Name the three subclasses of Class Mammalia.
Answer:

1. Marsupials
2. Monotremes
3. Eutheria

Question 17.
Name the three subfamilies of family Hominoidea.
Answer:

1. Hyalobatidae
2. Pongidae
3. Hominidae

Give the significance of the following

Question 1.
Significance of Natural selection
Answer:

1. Natural selection is the main driving force behind the evolution.
2. Natural selection favours those genetic variations which have better fitness value.
3. Such organisms are at selective advantage and they produce more offspring than the rest. Such organisms have greater survival and reproductive capacity.
4. In this way natural selection helps in the evolution of new species.
5. Natural selection favours differential reproduction of gene and brings about changes in the gene frequency.
6. Natural selection brings about evolutionary changes.
7. Natural selection also eliminates the genes carrying harmful mutations. This is called mutation balance in which allele frequency of harmful recessives remain constant generation after generation.

Distinguish between the following

Question 1.
Gene flow and Genetic drift.
Answer:

Gene flow	Genetic drift
1. Gene flow is the alteration in the gene frequency due to migrations.	1. Genetic drift is alteration in the gene frequency by pure chance.
2. Gene flow occurs due to exchange of genes in the adjacent populations through interbreeding.	2. Genetic drift occurs due to accidental and sudden elimination of a particular gene.
3. Larger populations tend to show more migrations and hence more gene flow.	3. Smaller populations have greater chances of genetic drift.
4. Gene flow occurs due to emigration and immigration.	4. Genetic drift occurs only within the specified population.

Question 2.
Directional, Stabilizing and Disruptive selection.
Answer:

Directional selection	Stabilizing selection	Disruptive selection
1. Natural selection operating in a linear direction is called directional selection.	1. Natural selection operating to balance or stabilize the population is called stabilizing selection.	1. Natural selection which disrupts the mean characteristics of a population is called disruptive selection.
2. In directional selection, more individuals acquire characters other than the mean character value.	2. In stabilizing selection, more individuals of a population acquire a mean character value.	2. In disruptive selection, more number of individuals acquire extreme or peripheral character value.
3. Directional selection eliminates one of the extremes of the phenotypic range and favour the other.	3. Stabilizing selection tends to favour the intermediate forms and eliminate both the phenotypic extremes.	3. Disruptive selection favours extreme phenotypes and eliminate intermediate.
4. It streamlines variations.	4. It reduces variations.	4. It increases variations.
5. This kind of selection is the most common.	5. This kind of selection is common.	5. This kind of selection is rare.
6. Directional selection operates for many generations, it results in an evolutionary trend within a population and shifting a peak in one direction. E.g. Industrial melanism, DDT resistance in mosquito, etc.	6. This selection leads to evolutionary change but tend to maintain phenotypic stability within population. E.g. All the populations which have adapted to their environment.	6. It ensures the effect on the entire gene pool of a population, considering all mating types or systems. E.g. African seed cracker finches with different sized beaks

Question 3.
Homologous organs and Analogous organs.
Answer:

Homologous organs	Analogous organs
1. Homologous organs are structurally similar to one another.	1. Analogous organs are structurally dissimilar to one another.
2. Homologous organs are functionally dissimilar from one another.	2. Analogous organs are functionally similar to one another.
3. Homologous organs help in tracing the evolutionary relationships.	3. Analogous organs do not help in tracing the evolutionary relationships.
4. Homologous organs lead to divergent evolution.	4. Analogous organs lead to convergent evolution.
5. Animals residing in different habitats but having closer evolutionary relationship show homologous organs. E.g. Forelimbs of frog, lizard, bird, bat, whale, man, etc.	5. Diverse animals residing in the similar habitat show analogous organs. E.g. Wing of a bird and wing of an insect.

Question 4.
Allopatric and Sympatric speciation.
Answer:

Allopatric speciation	Sympatric speciation
1. Allopatric speciation is the formation of a new species due to separation of a segment of population from the original population.	1. Sympatric speciation is the formation of species within single population.
2. There is geographical barrier cutting across the species range during such speciation.	2. There is no geographical isolation during sympatric speciation.
3. Allopatric speciation does not have physiological barrier.	3. Sympatric speciation is due to physiological or reproductive isolating barrier.
4. Migration of individual are also helpful in allopatric speciation. E.g. African elephant and Indian elephant.	4. Mutations are helpful in sympatric speciation. E.g. Cichlid fishes in Lake Victoria.

Give scientific reasons

Question 1.
Simple organic molecules did not show decomposition in primitive oceans.
Answer:
Simple organic molecules which were formed during chemical evolution, accumulated at the bottom of water bodies. At that time there was no free oxygen and enzymes. Therefore, simple organic molecules did not show decomposition in primitive oceans.

Question 2.
Archaeopteryx is called connecting link between reptiles and birds.
Answer:
(1) Archaeopteryx shows reptilian as well as avian characters.

(2) Reptilian characters are as follows:

• Jaws with homodont (all similar) teeth. Bones are nonpneumatic i.e. solid.
• Ribs have a single head. Sternum without keel.
• Abdominal ribs present which are like the crocodilian ribs.
• Forearms have three digits ending in distinct claws while the hind limb has four digits ending in clawed digits.

(3) Avian characters shown by it are as follows:

• Forearms modified into wings.
• Feathery exoskeleton.
• Skull bones are completely fused.
• Cranium is rounded with large orbits and a single condyle.
• Jaws are modified into beak.
• Limb bones have first toe in opposable manner. Foot present with clawed digits. Since it showed characters of both the classes, it is considered as the connecting link between the two.

Question 3.
Birds are glorified reptiles.
Answer:
Huxley, the evolutionary biologist gave this statement after studying the characters of birds and reptiles. The fossil bird, Archaeopteryx was discovered which showed characters of both Reptilia and Aves. It showed transformation of reptilian characters into bird characters. Hence, birds are said to be glorified reptiles with feathery exo-skeleton and other glorious characteristics.

Question 4.
Analogous organs do not have significant role in evolution.
Answer:
Analogous organs lead to convergent evolution, i.e. different organisms show same superficial structural similarities due to similar functions or habitat. But anatomically and structurally they are different. These organs do not help to trace the common ancestry. Therefore, they are said to have no significant role in evolution.

Question 5.
Australopithecus is described as a man with ape brain.
Answer:
(1) Australopithecus can be considered as a connecting link between ape and man due to the following ape-like and man like characteristics shown by it.

(2) The ape-like characteristics of Australopithecus:

• The jaws and teeth were larger than those of modern man.
• The face was prognathous, i.e. it had a muzzle like slope
• The chin was absent
• The eye-brow ridges projected over the eyes
• Their cranial capacity ranged from 450-600 c.c.

(3) The man-like characteristics of Australopithecus:

• It walked nearly or completely straight due to erect posture.
• The vertebral column had a distinct lumbar curve with broad basin-like pelvic girdle.
• Dentition was man-like with the smoothly rounded parabolic dental arch.
• A simian gap was absent. Australopithecus is therefore, rightly described as a man with ape brain.

Write short notes on the following

Question 1.
Evidences of Darwinism.
Answer:
(1) Height of neck of Giraffe : Long-necked Giraffe came into existence in the following way. Long-necked Giraffe could pluck and eat more leaves from tall trees and woody climbers. So it was well adapted to the environment. Short-necked one could not get food and thus perished in the struggle. This adaptation was transmitted to their offspring.

(2) Black colour peppered moths : The example of industrial melanism seen in U.K. is an excellent example of natural selection in action. Black coloured moths evolved gradually as new species from the previous white coloured forms.

(3) DDT resistance in mosquitoes : Intensive DDT spraying destroyed all types of mosquitoes. Some mosquitoes developed resistance to DDT and survived in spite of DDT spray. They reproduced more and were thus selected naturally.

Question 2.
Drawbacks and Objections to Darwinism.
Answer:

1. Darwin took into consideration minute fluctuating variation as principal factors. But these are neither heritable nor are part of evolution.
2. Darwin did not distinguish somatic and germinal variation and considered all variations are heritable.
   ‘Arrival of the fittest’ was not explained by him.
3. Darwin was unable to explain the cause, origin and inheritance of variations and of vestigial organs.
4. He also could not explain extinction of species.
5. Gradual accumulation of useful variations forms the new species, but their intermediate forms were not recognised.
6. Darwin could not explain existence of neutral flowers and the sterility of hybrids.

Question 3.
The main features of mutation theory.
Answer:

1. Mutations are large, sudden and discontinuous variations in a population.
2. Changes caused due to mutations are inheritable.
3. The raw material for organic evolution is provided by mutations.
4. Mutation can be useful or harmful. Useful mutations are at evolutionary advantage as they are selected by nature.
5. Accumulation of the useful mutations over a period of time leads to the origin and establishment of new species.
6. Harmful or non-adaptive mutation may persist or get eliminated by nature.

Question 4.
Directional selection.
Answer:

1. Natural selection bringing about directional change without disrupting the balance is called directional selection.
2. In a population when more individuals acquire characters which are other than the mean character value, then it is called directional selection.
3. Natural selection usually acts to eliminate one of the extremes of the phenotypic range and favour the other. E.g. systematic elimination of homozygous recessives.
4. Directional selection operates for many generations, it results in an evolutionary trend within a population and shifting a peak in one direction.
   E.g. Industrial melanism, DDT resistant mosquito, etc.

Question 5.
Stabilizing selection/Balancing selection.
Answer:

1. Stabilizing selection is the type of natural selection which balances the population, hence it is also known as balancing selection.
2. In such population more individuals acquire a mean character value.
3. Such selection tends to favour the intermediate forms and eliminate both the phenotypic extremes.
   E.g. More number of infants with intermediate weight survive better as compared to overweight or underweight infants.
4. Stabilizing selection reduces variations.
5. It tends to maintain phenotypic stability within population, and does not bring about drastic evolutionary changes.
6. A population showing stabilizing selection is well-adapted to its environment.

Question 6.
Homologous organs.
Answer:

1. The structural similarities between the homologous organs indicate that they have a common ancestry.
2. Different homologous organs indicate divergent evolution or adaptive radiation.
3. Homologous organs help in tracing the phylogenetic relationships.
4. Homologous organs are those organs which are structurally similar but functionally dissimilar.

E.g.
(i) Forelimbs of frog, lizard, bird, bat, whale and man are homologous to each other. All the limbs are morphologically similar in construction such as similar limb bones but are dissimilar in function. Frog limbs are meant for hopping, lizard limbs help in crawling, birds and bats fly with the . help of forelimbs while whale uses it for swimming and man for handling the objects.

(ii) Vertebrate heart and brain. & In plants, thorns of Bougainvillea and tendrils of Cucurbita represent homology.

Question 7.
Analogous organs.
Answer:

1. Analogous organs are similar in function but dissimilar in structural details.
2. They do not help to trace the relationship in the evolution but help to understand the convergent evolution.
3. Structural modifications in the organs are due to similar habitat.

E.g.
(i) Wing of an insect and wing of a bird, both are useful in flight so they are functionally similar but are structurally different. Insect wing is formed by exoskeleton expansion while bird wing is the modified forelimb.

(ii) Eye of the Molluscan octopus and of eye of mammals. They differ in their retinal position, structure of lens and origin of different eye parts, but both perform function of vision.

(iii) The flippers of penguins (birds) and dolphins (mammals).

(iv) Sweet potato which is a root modification and potato which is a stem modification, both perform similar function of storing starchy food.

Question 8.
Vestigial organ.
Answer:

1. Vestigial organs are rudimentary organs which are imperfectly developed and non¬functional, degenerate structures.
2. These organs in animals become functionless thus their presence in the body is not required.
3. But they are simply present as they descend down during evolution and continue to exist.
4. In the process of evolution, they may disappear totally.
5. They indicate evolutionary line as they were once functional in the ancestors.

Examples of vestigial organs in human beings:

1. Caecum and vermiform appendix : These are functional in herbivorous animals where they help in cellulose digestion. In humans they are functionless.
2. Nictitating membrane situated in the eyes of humans. It is a remnant of third eyelid.
3. Coccyx or tail vertebrae which shows remnant of tail, Wisdom teeth or 3rd molars. These organs indicate that human beings descended from ape like ancestors.

Question 9.
Types of fossils.
Answer:
There are four main types of fossils : actual remains, moulds, casts and compressions.
1. Actual remains : The most common type of fossil is actual remains in which the plants, animals and human bodies are seen embedded in permafrost of arctic or alpine snow. Due to severe cold temperature, the bodies remain preserved in the actual state, E.g., Fossil of Woolly Mammoth in Siberia. Many insects and smaller arthropods remained embedded and thus preserved in amber or hardened resin.

2. Moulds : Hardened encasements formed in the outer parts of organic remains of animals or plants form moulds. The organisms later decays leaving cavities or the impression in permanent form. E.g. Footprints.

3. Casts : Casts are hardened pieces of mineral matter which is deposited in the cavities of moulds.

4. Compressions : A thin carbon film indicates the outline of external features of ancient organism, but other structural details are not seen.

Question 10.
Major changes that occurred in human evolution.
Answer:

1. Major changes that took place in evolution of man are as follows :
2. Increase in size and complexity of brain and enhanced intelligence.
3. Increase in cranial capacity.
4. Bipedal locomotion.
5. Opposable thumb.
6. Erect posture.
7. Shortening of forelimbs and lengthening of hind limbs.
8. Development of chin. Orthognathous face.
9. Broadening of pelvic girdle and development of lumbar curvature.
10. Social and cultural development such as articulated speech, art, development of tools, etc.

Question 11.
Dryopithecus.
Answer:

1. Dryopithecus is also called Proconsul. Leakey discovered the fossils of Dryopithecus, on an island in Lake Victoria of Africa. Also the fossil was found in Haritalyanga in Bilaspur district of Himachal Pradesh.
2. It was a group of apes that lived in Miocene epoch about 20 to 25 million years ago.’
   Several species of Dryopithecus are available, the important among these is African fossil D. africanus.
3. Dryopithecus has a close similarity to chimpanzee and also walked like a modern chimpanzee.
4. The structure of its limbs and wrists show that knuckle walking was lesser in it. It used the flat of its hands like a monkey.
5. It had arms and legs of the same length and had a semi-erect posture.

Question 12.
Ramapithecus.
Answer:

1. Ramapithecus was on direct line of evolution of man.
2. It was called an ape-man like primate.
3. Its fossils were obtained in the form of teeth and jaw bones in the rocks of Siwalik Hills in India by Lewis and also in Kenya.
4. It existed during late Miocene and early Pliocene epoch about 14 to 12 million years ago.
5. It walked erect on its hind limbs.
6. It had close similarity with chimpanzee.
7. Some scientists believe that Dryopithecus evolved into Ramapithecus.

Question 13.
Australopithecus.
Answer:

1. Australopithecus is considered as connecting link between ape and man.
2. Its fossils were obtained from Toung valley in South Africa, from Ethiopia and Tanzania.
3. It was in late Pliocene or early Pleistocene epoch about 4 to 1.8 million years ago.
4. It was about 4 feet tall. It had prognathus face, with larger jaws. Chin was absent. Lumbar curvature was present.
5. It walked upright.
6. The cranial capacity was about 450 to 600 CC. Therefore, it was called man with ape brain.

Question 14.
Homo habilis.
Answer:

1. Homo habilis is described as Handy man. His fossils were obtained from Olduvai Gorge in Tanzania, Africa.
2. He existed in late Pliocene or early Pleistocene about 2.5 to 1.4 million years ago.
3. He was lightly built.
4. Fossil of lower jaw was obtained which showed that his dentition was more like modern man with small molars.
5. He walked erect. His cranial capacity was 640 to 800 cc.
6. He did not eat meat and made stone tools.

Question 15.
Homo erectus.
Answer:

1. Homo erectus was also known as Java man or Peking Man due to his fossils obtained from these areas.
2. He was also called ape man.
3. He lived in the middle Pleistocene epoch about 1.5 million years ago.
4. He was 5 feet in height with prognathous face, massive jaws, huge teeth and bony eye brow ridges.
   Chin was absent.
5. He walked erect.
6. The cranial capacity was 900 cc.
7. He was omnivorous and probably used fire and ate meat.

Question 16.
Neanderthal man.
Answer:

1. The scientific name of Neanderthal man is Homo neanderthalensis. He is described as advanced prehistoric man.
2. It was called Neanderthal man because its first fossil was collected from Neanderthal valley in Germany by Fuhlrott (1856).
3. It was heavily built and short and had outwardly curved thigh bones.
4. The facial features were as follows : prominent brow ridges, thick skull bones, low and slanting forehead, deep jaw without a chin, etc.
5. Neanderthal man existed in late Pleistocene epoch about 1,00,000 to 40,000 years ago. It was widely spread in Europe, Asia and North America. It became extinct about 25,000 years ago.
6. The cranial capacity of Neanderthal man was about 1400 cc, which was roughly equal to that of modern man. He used hide for dressing.
7. It showed intellectual development in constructing and using flint tools and fire.
8. The Neanderthal men used to bury their dead bodies along with their tools and perform ceremonies.

Short answer questions

Question 1.
Enlist the steps in the process of chemical evolution.
Answer:

1. Origin of Earth and Primitive atmosphere.
2. Formation of ammonia, water and methane.
3. Formation of simple organic molecules.
4. Formation of complex organic molecules.
5. Formation of Nucleic acids.
6. Formation of Protobionts or Procells.
7. Formation of first cell.

Question 2.
When did Earth originate? Which transformations took place later?
Answer:

1. Earth originated about 4.6 billion years ago as a part of the solar system.
2. When it was formed, it was a rotating cloud of hot gases and cosmic dust. It was then appearing like a nebula.
3. Later the condensation and cooling started which resulted in stratification.
4. Heavier elements like nickel and iron settled to the core. Lighter elements like helium, hydrogen, nitrogen, oxygen, carbon, etc. remained on the surface and they formed the primitive atmosphere.
5. This atmosphere of the earth was of a reducing type, devoid of free oxygen and very hot.

Question 3.
How were simple organic molecules formed on the earth?
Answer:
1. Initially earth’s temperature was very high but as the cooling process started, lighter elements reacted chemically with each other.

2. The early atmosphere was rich in hydrogen, carbon, nitrogen and sulphur. Hydrogen was most active and hence it reacted with other elements to form chemicals on earth like CH4, NH3, H20 and H2S.

3. With decreasing temperature of the earth, steam condensed into water that resulted in heavy rainfall. This constantiy falling rainwater got accumulated on the land to form different water bodies and especially oceans. It also cooled down the earth.

4. The early molecules of hydrocarbons, ammonia, methane and water underwent reactions like condensation, polymerisation, oxidation and reduction due to different energy sources such as ultra-violet rays, radiations, lightning and volcanic activities.

5. These reactions resulted in formation of simple organic molecules like monosaccharides, amino acids, purines, pyrimidines, fatty acids, glycerol, etc.

Question 4.
How were complex organic molecules formed during chemical evolution?
Answer:

1. The primitive broth in which simple organic molecules were suspended, was neutral and free from oxygen.
2. In this broth polymerisation took place and simple organic molecules aggregated to form new complex organic molecules like polysaccharides, fats, proteins, nucleosides and nucleotides.
3. Protoproteins were formed by polymerisation of amino acids. These protoproteins later formed proteins.
4. Formation of protein molecules is considered as landmark in the origin of life. Later the enzymes were formed which accelerated the rate of other chemical reactions.

Question 5.
How were protobionts formed with the help of nucleic acids during chemical evolution?
Answer:

1. By the reaction between phosphoric acid, sugar and nitrogenous bases (purines and pyrimidines), nucleotides may have been formed.
2. These nucleotides joined together to form nucleic acids such as RNA and DNA.
3. Nucleic acids acquired self-replicating ability which is a fundamental property of living form.
4. They later formed protobionts. They were the first form of life formed by nucleic acids along with inorganic and organic molecules.
5. Protobionts were the prebiotic chemical aggregates having some properties of living system. Aggregation of organic molecules due to coacervation formed these protobionts.

Question 6.
Why variations are seen in population?
Answer:
Variations are seen in population due to gene flow, genetic drift, genetic recombinations that occur at the time of gamete formation, crossing over and sudden drastic changes like gene mutations or chromosomal aberrations. All the above factors are constantly operating over every population. Due to these evolutionary processes, variation take place in a population.

Question 7.
In which conditions the gene frequency of a population will remain constant?
Answer:
In the condition of no migrations of the organisms, no mutations, no sexually reproduction consisting of crossing over, no genetic drift, no recombinations and variation, the gene frequency of a population will remain constant. Such hypothetical conditions will never exist because even one set of sexually reproducing organisms forms an offspring which is slightly different from its parents. This means that there is constant change of gene frequency.

Question 8.
What is carbon dating and how does it work?
Answer:
Carbon dating is the method to find out the age of the fossil or any other organic matter. In carbon dating, the relative proportions of the carbon isotopes, carbon-12 and carbon-14 which are present in the organic matter, is estimated. The ratio between them changes as radioactive carbon-14 decays and is not replaced by exchange with the atmosphere. From these findings the age of that organic matter can be concluded.

Question 9.
What is a connecting link? Give suitable examples of connecting links.
Answer:

1. A connecting link is an intermediate or transitional state between two systematic groups of organisms.
2. It bears characters common to both these groups on either side of its position. Thus it represents an evolutionary line.
3. Connecting links are also called a missing link.
   E.g. Archaeopteryx, the extinct bird is a connecting link between Reptiles and Aves.
4. Seymouria is a connecting link between Amphibia and Reptilia.
5. Ichthyostega is a connecting link between Pisces and Amphibia.

Question 10.
What is geological time scale? How is it divided ?
Answer:

1. Geological time scale is the arrangement of major divisions of geological time into eras, periods and epochs on the time scale.
2. This division is based on the study of fossilized organisms obtained from the different strata of the earth.
3. The characteristic significant events that occurred in the organization of organisms helped the geologists to understand the geological time scale.
4. The major divisions of geological time are called eras.
5. The eras are divided into periods and the periods into epochs.
6. By studying fossils in the earth crust, the evolutionary changes in the organisms have been traced out.

Question 11.
What is meant by palaeontological evidences ?
Answer:

1. Palaeontology means the study of fossils. Palaeontological evidences are the fossilized forms of various organisms which are obtained from different strata of the earth. They represent the dead remains of plants and animals that lived in the past in various geological layers.
2. The older and more primitive forms of life are excavated from the lower strata of the soil whereas the recent ones are situated on the upper layers of the soil.
3. Fossils are formed in variety of materials such as sedimentary rocks, amber, volcanic gas, ice, peat bogs, soil, etc.
4. They provide the true, direct and reliable evidences of evolution.

Question 12.
What are the molecular evidences that show the evolution?
Answer:

1. Different organisms have basic similarities in their molecules and the cellular constituents.
2. All living organisms have the same basic structural and functional unit, i.e. cell.
3. Cell organelles such as endoplasmic reticulum, Golgi bodies, mitochondria, etc. are present in different types of organisms.
4. Proteins and gene performing different functions have the same basic pattern which shows a common ancestry.
5. Catabolic activities of liberating energy, synthesis of macromolecules such as proteins, carbohydrates, nucleic acids, etc. are similar in different organisms.
6. ATP is the common energy currency of all the organisms.
7. All the above facts are called molecular evidences in favour of evolution.

Question 13.
Arrange the following stages of the human evolution in the order of their increasing cranial capacity, (a) Neanderthal man (b) Cro-Magnon man (c) Homo erectus (d) Homo habilis.
Answer:

1. Homo habilis (650-800 cc)
2. Homo erectus (850-1200 cc)
3. Neanderthal man (1400 cc)
4. Cro-Magnon man (1450 cc)

Question 14.
Since your earlier school days you have been solving mysteries/puzzles labelled as use your brain power. Did you ever wonder why human brain has such a capacity? Why and how we evolved along these lines? What is the extent of similarity between humans, chimpanzees and monkeys?
Answer:
Human beings have extremely well- developed brain. Especially the cerebral hemispheres are very large constituting 85% of the brain weight. Due to such cerebrum, there are many, neurons. They are responsible for faculties such as speech, memory, emotions, thought process. The mind or psyche is well developed due to over developed cerebral hemispheres.

That’s why human brain has tremendous capacity of Chimpanzees are also comparatively more intelligent than the monkeys. However, the development of speech and language is lacking in them. The cranial capacity of chimpanzee and monkey is 275-500 cc and 45-50 cc respectively, whereas humans have 1450-1500 cc. Larger the brain, more is the intelligence and all other mental faculties which only humans show.

Question 15.
Even though the cranium of elephant is larger than that of man, humans are considered more intelligent than elephant. Why is it so?
Answer:
Elephant’s brain is large weighing about 5 kg. But elephant’s body weight too is very high. The proportion of body brain weight is highest in human beings. Therefore, humans are considered more intelligent than elephant. Moreover, the cerebral cortex of elephant is not very well developed, instead they have well developed cerebellum which helps in locomotion and balancing their huge bodies. Human brain has very well-developed cerebrum which brings about cognitive behaviour and intelligence.

Chart based/Table based questions

Question 1.
Give the graphical representation of Hardy-Weinberg’s principle in the form of Punnet square.
Answer:

Genotypes = AA + 2 Aa + aa
Gene frequencies = p² + 2pq + q²

Question 2.
Make a chart showing the types of isolating mechanisms.
Answer:

Diagram based questions

Question 1.
Give diagrammatic representation to show RNA world.
Answer:

Question 2.
Sketch and label four types of chromosomal aberrations
Answer:

Question 3.
Sketch the graphs to show directional and stabilizing selection.
Answer:

Long Answer Questions

Question 1.
Write about four old theories which suggested about how did life originate on the earth.
Answer:
1. Theory of special creation : Theory of special creation is the oldest theory which is based on religious beliefs. According to this theory, all the living organisms were created by supernatural power. However, since there are no scientific proofs to this theory, it is not accepted.

2. Cosmozoic theory/Theory of Panspermia : This theory says that life did not originate on the earth but it was exported from the other planets in the form of biological spores or microorganisms which were named as cosmozoa or panspermia. They may have descended to the earth from other planets. Recently, NASA has reported fossils of bacteria-like organisms on a piece of Martian rock recovered from Antarctica. Such facts may throw some light on the cosmozoic theory.

3. Theory of spontaneous generation or Abiogenesis : There was a belief that life originated from non-living material spontaneously. This theory was later disproved by Louis Pasteur.

4. Theory of biogenesis : This theory says that living organisms can originate only from pre-existing living beings. It is same as reproduction. But this theory of biogenesis was unable to explain origin of life on earth. It explains only the continuity of life.

Question 2.
Haldane described ‘Hot dilute soup’ in his theory. Describe how this soup led to formation of some important molecules.
Answer:
(1) The primitive sea containing molecules of organic substances without free oxygen was described as ‘hot dilute soup or primitive broth’ by Haldane. He proposed the theory of chemical evolution.

(2) According to this theory, the chemical evolution took place in the following steps : (a) Origin of earth and its primitive atmosphere, (b) Formation of ammonia, water and methane. These molecules dissolved in rainwater and formed the seas, (c) Then synthesis of simple organic compounds took place, followed by formation of complex organic compounds such as nucleic acids.

(3) The early molecules underwent chemical reactions such as condensation, polymerization, oxidation and reduction.

(4) The biologically important molecules such as monosaccharides, amino acids, purine, pyrimidine, fatty acids and glycerol were formed due to these reactions, utilizing the sources of energy on the primitive earth.

(5) Since oxygen was lacking, there was no degradation. Enzymes were also absent and hence there was formation of complex molecules in the hot dilute soup.

(6) This further led to the formation of pre-cells or protobiont. These aggregates were called coacervates by Oparin or microspheres by Sidney Fox. This further gave rise to first cells on the earth.

Question 3.
Explain the process of formation of eobionts.
Answer:

1. Protobionts or coacervates were colloidal aggregations of hydrophobic proteins and lipids (lipoid bubbles).
2. They grew in size by taking up material from surrounding aqueous medium.
3. During their growth they became thermodynamically unstable and split into smaller units. These were called microspheres.
4. They were proteinoids formed from colloidal hydrophilic complexes surrounded by water molecules.
5. These bodies were like primitive cells having outer double-membrane. Across this membrane diffusion and osmosis may have occurred. They were more stable than coacervates.
6. Coacervates and microspheres were non-living colloidal aggregations of lipids and proteinoids respectively.
7. But they showed growth and division like living cells.
8. These colloidal aggregations turned into first primitive living system called eobionts or protocell.

Question 4.
Describe RNA World hypothesis.
Answer:

(1) RNA world hypothesis is based on discovery of catalytic RNA or ribozymes. It was proposed by Carl Woese, Francis Crick and Leslie Orgel in 1960 whereas Ribozymes were discovered by Sidney Altman and Thomas Cech in 1980.

(2) According to this hypothesis, early life must have been based most probably on RNA.

(3) Factors supporting this hypothesis are:

• RNA is found abundantly in all living cells.
• It is structurally related to DNA.
• Chains of RNA can evolve or undergo mutations, replicate and catalyse reactions.
• Biomolecules like Acetyl-Co-A have a nucleotide in their molecular structure.
• Ribosome acts as a protein assembly unit in the cell and is seen in many types of cells.
• In ribosomes, translation process is catalysed by RNA.

(4) The primitive molecules underwent repeated replication and mutation forming varieties of RNA molecules with varying sizes and catalytic properties.

(5) They later developed their own protein coats and machinery to survive the assembly of primitive cell.

(6) From them DNA was developed which was double stranded stable structure.

(7) It further kept on evolving giving rise to rich biodiversity on earth.

Question 5.
Explain in brief Darwinism and its five main postulates.
Answer:
Darwinism means theories of natural selection and speciation as put forth by Charles Darwin. The five main postulates of his theories are as follows: Overproduction or prodigality, Struggle for existence, Organic variations, Natural selection, Origin of new species (speciation).
1. Overproduction (Prodigality of nature) : There is a natural tendency to produce more number of progeny in geometric ratio for continuing the species. E.g. Salmon fish produces about 28 lakh eggs in a single season. Single pair of elephants would produce 19,000,000 elephants. But the size of given species in a given area remains relatively constant because of fluctuations that occur seasonally.

2. Struggle for existence Due to over¬production there is struggle for existence between the members of population for limited supply of food or to overcome adverse environmental conditions or for a space or to escape from enemies, etc.

3. Organic variations : There are differences in morphology, physiology, nutrition, habit, behavioural patterns, etc., among the members of same species or members of different species. These variations act as raw material for evolution.

4. Natural selection : Some organisms possess better variations to get adapted and survive under existing environmental conditions, while some do not have. Better adapted organisms are selected by the nature while those with unfavourable variations perish. The principle by which useful variations are preserved by nature, is called ‘Natural Selection’. It is also called ‘survival of fittest’ by H. Spencer.

5. Origin of new species (speciation) : Favourable variations are transmitted from generation to generation, resulting into better adapted generations. Gradually these adaptations with few new modifications become fixed in the life cycle, forming a new species.

Question 6.
Explain modern Synthetic Theory of Evolution in brief.
Answer:
(1) Modern synthetic theory of evolution is the result of modification of Darwinism and theory of mutations by taking into consideration studies of genetics, ecology, anatomy, geography and palaeontology.

(2) Five key factors of modern synthetic theory are gene mutations, mutations in the chromosome structure and number, genetic recombinations, natural selection and reproductive isolation. All these finally contribute in the evolution of new species or process of speciation.

(3) Population or Mendelian population is the small group of ‘interbreeding populations’. For every Mendelian population there is a gene pool which is constituted by total number of genotypes in it. The genotype of an organism in a population is constant, but the gene pool constantly undergoes change due to different factors such as mutations, recombination, gene flow, genetic drift, etc.

(4) Every gene has two alleles. The proportion of a particular allele in the gene pool, to the total number of alleles at a given locus, is called gene frequency. Thus any change in the gene frequency in the gene pool affects population.

(5) The five main factors are broadly divided into three main concepts as follows:
(i) Genetic variations caused due to various aspects of mutation, recombination and migration. Such variations cause change in the gene frequency. Gene mutations or point mutation change the phenotype of the organism, leading to variation. Recombination is caused due to crossing over in which new genetic combinations are produced. Sexual reproduction due to fertilization of gametes also cause recombinations. All these lead to variations, Gene flow is movement of genes into or out of the population, either due to migrations or dispersal of gametes.

Gene flow therefore change the gene frequencies of the population. Genetic drift is a random change which occurs by pure chance. It occurs in small populations but change the gene frequency. Chromosomal aberrations are structural or morphological changes in the chromosomes causing rearrangement of the sequence of genes.

(ii) Natural selection is said to be the main driving force in evolution. It brings about evolutionary changes by selecting favourable gene combinations by differential reproduction of genes. This brings about changes in gene frequency from one generation to next generation.

(iii) Isolation means the separation of the population of a particular species into smaller units which prevents interbreeding between them. This over a long time period leads to speciation or formation of new species.

Question 7.
What are different types of chromosomal aberrations?
Answer:

Chromosomal aberrations:
(1) The structural, morphological change, which take place in chromosome due to rearrangement, is called chromosomal aberrations.

(2) The aberrations change the sequence of the genes. This causes variations. Chromosomal aberrations are mainly of following four types:

1. Deletion : Loss of genes from chromosome.
2. Duplication : Genes are repeated or doubled in number on chromosome.
3. Inversion : A particular segment of chromosome is broken and gets reattached to the same chromosome in an inverted position due to 180° twist. There is no loss or gain of gene complement of the chromosome.
4. Translocation : Transfer or transposition of a part of chromosome or a set of genes to a non-homologous chromosome is called translocation. It is effected naturally by the transposons present in the cell.

Question 8.
What are the different pre-zygotic isolating mechanisms?
Answer:
(1) Pre-zygotic or pre-mating isolating mechanisms do not allow individuals to mate with each other at all.

(2) By various mechanisms the two groups remain isolated. These mechanisms are of following types:
(i) Habitat isolation : Habitat isolation is the phenomenon in which members of a population living in the same region occupy different habitats. Hence the potential mates do not interbreed among themselves.

(ii) Seasonal isolation : In seasonal isolation, members of a population share the same region but attaining sexual maturity at the different times of the year. They thus remain isolated reproductively preventing interbreeding among themselves.

(iii) Ethological isolation : Ethological isolation is seen when members of two populations have different mating behaviours. This prevents interbreeding.

(iv) Mechanical isolation : Mechanical isolation is seen when the members of two populations have differences in the structure of reproductive organs. Due to such differences interbreeding is not possible.

Question 9.
What are the different post-zygotic isolating mechanisms?
Answer:

1. In post-zygotic or post-mating isolating mechanisms, the two individuals can mate but the result of mating is not favourable.
2. Thus the populations remain isolated without the actual genetic exchange.

Post-mating isolating mechanisms are divided into the following categories:

1. Gamete mortality : In gamete mortality, there is death of gametes. Sperm transfer may take place but the egg is not fertilized due to gamete mortality.
2. Zygote mortality : In zygote mortality, the zygote is formed but it fails to thrive. Though the egg is fertilized the zygote does not survive.
3. Hybrid sterility : In this isolation, there is the formation of hybrid as the gametes or zygotes do not die but the hybrid formed is sterile. Sterile hybrid cannot contribute genetically to further generations.

Question 10.
What is Hardy-Weinberg equilibrium? Explain it in brief.
Answer:

1. Hardy and Weinberg were two scientists who proposed a concept of genetic equilibrium popularly known as Hardy- Weinberg principle or equilibrium.
2. This principle states that gene, allele or genotype frequencies remain the same from generation to generation unless disturbed by factors like mutation, non-random mating, genetic drift, etc.
3. For explaining the concept of equilibrium they assumed that there are two alleles located at a single locus (A and a).
4. Their respective frequencies are p and q.
5. The frequency of genotype AA is p, for 2Aa is 2pq and for aa is q.
6. The equilibrium equation is p² + 2pq + q² = 1
7. It says that if sum total of gene frequencies is 1, then sum total of genotype frequencies is also equal to 1. When the equilibrium is disturbed then only evolution occurs.

Question 11.
Human being is said to be most evolved, intelligent living being. Yet we are not self-sufficient. Think of various aspects for which we depend on other living beings for our survival.
Answer:
Human brain is evolved and super- specialised but yet in many aspects human beings are much dependent on other natural factors. Human body is not with any protective exoskeleton, or organs of offence and defence.

Unless well dressed, he cannot cope up with severe cold temperatures as he lacks natural protective fur. He cannot run fast as the other animals can. Neither he can digest uncooked food. He has overcome all his shortcomings by using his brain power.

He has managed to take fur and feathers from other animals by killing them. He also uses other natural fibres from plants to cover his body. He has also finished fish from the oceans by over-exploitation and polluting the natural habitats of these creatures.

He takes meat from other animals by killing them and for the purpose he domesticates them to satisfy his hunger. Before technical age, animals were used as beasts of burden and as means of transport. Thus human history has shown excessive use of horses, camels, elephants, etc.

Man snatches milk from other animals like cows and buffaloes which is for their young ones. But the entire diary industry and human needs for dairy products have been taken care of by these herbivores.

Apart from all such uses, man also uses other animals for experimentations and pharmaceutical industries. In this way, man has mastered other animal kingdom due to his intelligence.

Balbharti Maharashtra State Board Class 11 Geography Important Questions Chapter 1 Earth Movements Important Questions and Answers.

Maharashtra State Board 11th Geography Important Questions Chapter 1 Earth Movements

Complete the chain.

Question 1.

A	B	C
(1) P-waves	(1) Ring of Fire	(1) Indonesia
(2) Volcanic eruption	(2) Shadow zone	(2) Italy
(3) Cinder cone	(3) Smoke	(3) Cauliflower cloud
(4) Tectonic movements	(4) Mt. Nuovo	(4) Cotopaxi
(5) Circum pacific belt	(5) Convergent and divergent margin	(5) Between 105° and 140°

Answer:

A	B	C
(1) P-waves	(1) Shadow zone	(1) Between 105° and 140°
(2) Volcanic eruption	(2) Smoke	(2) Cauliflower cloud
(3) Cinder cone	(3) Mt. Nuovo	(3) Italy
(4) Tectonic movements	(4) Convergent and divergent margin	(4) Indonesia
(5) Circum pacific belt	(5) Ring of Fire	(5) Cotopaxi

Choose the correct option by identifying the correct correlation in the sentences.

Question 1.
Formation of mountains and distribution of continents are related to ……………
(a) sudden movements
(b) slow movements
(c) vertical movements
(d) horizontal movements
Answer:
(b) slow movements

Question 2.
A fold where one limb lies over the other in horizontal direction is ………………
(a) symmetrical fold
(b) overturned fold
(c) recumbent fold
(d) isoclinal fold
Answer:
(c) recumbent fold

Question 3.
Young fold mountains are of ………………… age.
(a) 10 to 25 million years
(b) over 200 million years
(c) 25 to 40 million years
(d) 30 to 45 million years
Answer:
(a) 10 to 25 million years

Question 4.
The tensional forces may cause subsidence in the central portion of the crust between two adjacent faults forming …………………
(a) rift valleys
(b) lava domes
(c) fold mountain
(d) volcanic mountain
Answer:
(a) rift valleys

Question 5.
P-waves can pass through ………………….
(a) only solid medium
(b) only liquid medium
(c) all mediums
(d) air
Answer:
(c) all mediums

Question 6.
When the lava solidifies in the volcanic neck, it forms …………….
(a) caldera
(b) cinder cone
(c) crater
(d) volcanic plug
Answer:
(d) volcanic plug

Question 7.
When a portion of landslides down along the fault plane and when the exposed portion of the plane faces the sky ………….. is formed.
(a) reverse fault
(b) normal fault
(c) thrust fault
(d) tear fault
Answer:
(b) normal fault

Question 8.
Faulting results in the formation of ……………….
(a) volcanic mountains
(b) block mountains
(c) fold mountains
(d) volcanic plateaus
Answer:
(b) block mountains

Question 9.
A specific area where the seismic waves are not reported is called a ……………….
(a) shadow zone
(b) epicentre
(c) focus
(d) fracture zone
Answer:
(a) shadow zone

Question 10.
The describes the intensity of an earthquake based on its observed effects.
(a) Richter scale
(b) Mercalli scale
(c) seismogram
(d) seismograph
Answer:
(b) Mercalli scale

Question 11.
Sometimes, the lava material thrown into the air solidifies into small fragments before falling on the surface; it is called ………………
(a) crock fragments
(b) ash
(c) volcanic dust
(d) volcanic bombs
Answer:
(d) volcanic bombs

Question 12.
The …………….. are symmetrical in shape.
(a) cinder cone
(b) lava domes
(c) volcanic plateau
(d) composite cone
Answer:
(d) composite cone

Question 13.
Earthquakes are recorded with the help of ………………. instrument.
(a) seismogram
(b) seismograph
(c) Richter scale
(d) Mercalli scale
Answer:
(b) seismograph

Identify the correct correlation.

Question 1.
A – The origin of Himalayas is due to the collision of the Indian subcontinent with Eurasian landmass.
R – The convergence of plates is often associated with mountain building.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(c) Both A and R are correct and R is the correct explanation of A.

Question 2.
A – The structure of the interior of the earth is decided with the help of seismic waves.
R – The S-waves travel in solid, liquid and gaseous medium while P-waves travel only through solid medium.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(a) Only A is correct.

Question 3.
A – Volcanic activity coincides with seismic activity of the world.
R – The seismic cone coincides with plate boundaries.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(d) Both A and R are correct but R is not the correct explanation of A.

Question 4.
A – Basic lava contains less percentage of silica.
R – It has high melting point.
(a) Only A is correct.
(b) Only R is correct.
(c) Both A and R are correct and R is the correct explanation of A.
(d) Both A and R are correct but R is not the correct explanation of A.
Answer:
(a) Only A is correct.

Identify the incorrect factor.

Question 1.
The types of fold are-
(a) symmetrical
(b) recumbent
(c) Isoclinal
(d) Reverse
Answer:
(d) Reverse

Question 2.
The types of fault are-
(a) overturned
(b) reverse
(c) Thrust
(d) Tear
Answer:
(a) overturned

Question 3.
Causes of earthquake are-
(a) tectonic movements
(b) anthropogenic causes
(c) landslides
(d) Volcanicity
Answer:
(c) landslides

Question 4.
The solid material thro wn out of volcano consists of-
(a) soil
(b) volcanic bomb
(c) breccias
(d) Ash
Answer:
(a) soil

Question 5.
The material thrown out in formation of cinder cone are-
(a) ash
(b) cinder
(c) breccias
(d) Dust
Answer:
(d) Dust

Question 6.
Three major belts of earthquake and volcanoes are-
(a) Mid-Atlantic belt
(b) Mid-continental belt
(c) Circum-Pacific belt
(d) Indian Ocean belt
Answer:
(d) Indian Ocean belt

Question 7.
Three types of seismic waves are-
(a) P-waves
(b) S-waves
(c) F-waves
(d) longitudinal waves
Answer:
(c) F-waves

Question 8.
Examples of block mountain are-
(a) Black Forest Mountains in Germany
(b) Satpuras in Maharashtra
(c) Vosges in France
(d) Himalayas in India
Answer:
(d) Himalayas in India

Identify the correct group.

Question 1.

A	B	C	D
(1) Mt. Fujiyama	(1) Normal Fault	(1) Rock Fragments	(1) Crater Lake
(2) Mt. St. Helens	(2) Reverse Fault	(2) Volcanic Dust	(2) Caldera
(3) Pinatubo	(3) Tear Fault	(3) Inflammable gases	(3) Volcanic Plug
(4) Mayon	(4) Overturned fold	(4) Biotic Material	(4) Volcanic Plateau

Answer:
C

Question 2.

A	B	C	D
(1) Asymmetrical Fold	(1) Normal Fault	(1) Zone I – Very high intensity	(1) Limb
(2) Overturned Fold	(2) Thrust Fault	(2) Zone II – High intensity	(2) Anticline
(3) Isoseismal Lines	(3) Reverse Fault	(3) Zone III – Moderate intensity	(3) Syncline
(4) Symmetrical Folds	(4) Tear Fault	(4) Zone IV – Low intensity	(4) Trough

Answer:
C

Give geographical reasons.

Question 1.
Faulting results in formation of block mountains.
Answer:
Faulting results in formation of block mountains because-

1. Earth movements generate tensional forces that tend to pull the crust apart and faults are developed.
2. If the block enclosed by the faults rises above or the land on either side subsides, the upstanding portion becomes the block mountain.
3. The Black forest mountain in Germany, Vosges in France, Satpuras in Maharashtra are examples of block mountains.

Question 2.
The crust of the earth shakes.
Answer:
The crust of the earth shakes because –

1. Movements occurring in the crust of the earth produce a lot of stress in the rock strata.
2. When this stress accumulates beyond a limit, it tends to get released in the crust.
3. Release of stress causes release of energy.
4. The release of energy produces energy waves and this makes the earth’s crust to shake.

Question 3.
A zone between 105° and 140° from the epicentre is identified as the shadow zone for P and S waves.
Answer:
A zone between 105° and 140° from the epicentre is identified as the shadow zone for P and S waves because-

1. Generally, seismographs located at any distance within 105° from the epicentre, record the arrival of both P-waves and S-waves.
2. However, the seismographs located beyond 140° from the epicentre; record the arrival of P-waves but not that of S-waves.
3. The shadow zone results from S-waves being stopped entirely by the liquid core and P-waves being bent (refracted) by the liquid core.

Question 4.
Volcanic eruptions can cause earthquakes.
Answer:
Volcanic eruptions can cause earthquakes because-

1. Most of the earthquakes are along the edges of tectonic plates. This is where most volcanoes are too.
2. Most earthquakes directly beneath a volcano are caused by the movement of magma.
3. The magma exerts pressure on the rocks until it cracks the rock.
4. Then the magma flows out into the cracks building pressure again. Every time the rock cracks it makes a small earthquake.

Question 5.
Most of the volcanoes are found along plate boundaries.
Answer:
Most of the volcanoes are found along plate boundaries because-

1. Volcanoes are common along convergent and divergent plate boundaries.
2. They are also associated with meeting zones of continents and oceans.
3. Volcanoes erupt because mantle rock melts, due to extremely high temperatures, and pressure.
4. Along the subduction plate boundaries, the crust heats up as it sinks into the mantle, resulting into upwelling of lava.

Differentiate between.

Question 1.
Volcanoes and Earthquakes.
Answer:

Volcanoes	Earthquakes
(i) Volcanoes form at the earth’s surface.	(i) Earthquakes originate from deeper within the crust.
(ii) Volcanoes are formed by release of gases and magma.	(ii) Earthquakes are caused by movement along a fault.
(iii) Volcanoes lead to formation of new landforms like domes, plateaus, cones, caldera etc	(iii) Earthquakes simply cause waves which disturb rocks they do not form any landforms.
(iv) It directly produces ash and other volcanic debris.	(iv) Earthquake events does not directly produce debris. But debris results by destruction due to the earthquake.
(v) It is possible to predict a volcanic eruption a few weeks to a few days in advance, though the exact time of eruption can’t be predicted with any accuracy.	(v) The likelihood of an earthquake can be predicted but it is not possible to determine any time frame of when the earthquake will take place, or how likely it is to happen at some point in future.

Question 2.
Acid lava and Basic lava.
Answer:

Acid lava	Basic lava
(i) It contains high percentage of silica.	(i) It contains less percentage of silica.
(ii) It has got high melting point.	(ii) It has low melting point.
(iii) It is thick, fluid and moves slowly.	(iii) It is more fluid and can flow over long distance.

Mark and name the following on the outline map of the world with suitable index.

(1) Ring of Fire
(2) Indo-Australian plate
(3) Eurasian Plate
(4) Pacific Plate
(5) Mt. Cotopaxi
Answer:

Answer the following Questions by using the given map

Question 1.
Name the volcanic mountain in Africa.
Answer:
Kilimanjaro

Question 2.
Name the volcanic mountain in Pacific Ocean.
Answer:
Mauna Loa

Question 3.
Name the volcanic mountain in Japan.
Answer:
Fuji

Question 4.
Name volcanic mountain in Europe.
Answer:
Stromboli

Question 5.
Name the volcanic mountain along the north eastern coastline of North America.
Answer:
St. Helens

Write short notes on.

Question 1.
Folding
Answer:

1. Folding occurs when compressional forces are applied to rocks that are ductile or flexible.
2. Rocks that lie deep within the crust and are therefore under high pressure are generally ductile and particularly susceptible to folding without breaking.
3. As a result, rocks deep within the crust typically fold rather than break.
4. Folding is also likely to occurs where compressional forces are applied slowly.
5. Folding results into formation of fold mountains e.g., the Himalayas, the Alps etc.
6. There are different parts of folds – limbs, axis of fold, Anticline, syncline, axial plane.
7. There are different types of fold formed on basis of inclination of limbs – symmetrical fold, asymmetrical fold, overturned fold, recumbent fold and isoclinal fold.
8. The nature of fold depends on several factors like, the nature of rocks, the nature and intensity of compressive forces, duration of the operation of compressive forces, etc.

Question 2.
Faulting:
Answer:

1. In the earth’s crust, the forces operating in opposite direction lead to tension.
2. As a result, rocks develop cracks or fissure.
3. In the regions where cracks develop rocks get displaced, such displacement can occur in upward downward or horizontal direction.
4. Faulting can be classified according to displacement of rocks.
5. Rock layers that are near the earth’s surface and not under high confining pressures are too rigid to bend into folds.
6. If the tectonics force is large enough, these rocks will break rather than bend. Such breaks may also be called fracture, ruptures or faults.
7. Faulting results in formation of block mountains and rift valleys.
8. There are different types of faults – normal faults, reverse faults, tear fault and thrust fault.

Question 3.
Types of faults
Answer:
A fault is a fracture in the crustal rock, formed when the crustal rocks are displaced due to tensional movement caused by endogenic forces. The displacement of rock can occur in upward, downward different or horizontal direction.
The types of faults determined by the direction of motion are:

1. Normal fault: It results when portion of land slides down along the fault plane and when the exposed portion of the plane faces the sky.
2. Reverse fault: It results when a portion of the land is thrown upward relative to other side of the land. In such situation, the fault plane faces the ground.
3. Tear fault : At times, the rock strata on either side of the fault plane do not have vertical displacement. Instead, movement occurs along the plane in horizontal direction.
4. Thrust fault: When the portion of the land on one side of the fault plane gets detached and moves over the land on the other side. The angle of fault plane is generally less than 45°.

Question 4.
Types of folds
Answer:
Folding occurs when compressional forces are applied to rocks, that are ductile or flexible.
The different types of folds are:
Symmetrical folds:

1. The axial plane is vertical.
2. The limbs are inclined at the same angle.

Asymmetrical folds:

1. The axial plane is inclined.
2. The limbs are inclined at different angles.

Overturned fold:

1. One limb lies above the other limb.
2. Limbs slope unequally in the same direction.

Recumbent fold:

1. Axial plane is almost horizontal.
2. One limb lies over the other in horizontal direction.

Isoclinal fold:

1. The limbs slope in the same direction with same amount.
2. The axial plane may be vertical, inclined or horizontal.
3. Slope of some portion of limbs is near vertical.

Question 5.
Volcanic landforms
Answer:
A number of landforms are formed due to cooling and solidification of magma. Some important landforms are as follows :
Lava Domes :

1. Domes are developed when magma comes out and solidifies around its mouth.
2. The shape of the dome depends upon the fluidity of lava.
3. High dome with steep slope is developed by acidic lava.
4. Due to basic lava, broad-based low domes are developed.

Lava Plateaus:

1. Due to spread of lava in huge quantity from fissure volcano, it covers large areas and plateaus are formed.
2. The Deccan Trap in India has developed from volcanic eruptions millions of years ago.

Caldera:

1. At times, the eruption of volcano brings about large quantity of material and relieves lot of pressure.
2. After the eruption, a large and deep depression remains in that area. This large depression is called caldera.
3. These can be around 10 km wide and hundreds of metres deep.
4. They may later turn into lakes. Smaller calderas are known as craters.

Crater Lake:

1. When the funnel shaped crater of an extinct volcano gets filled with rain water, it forms a crater lake.

Volcanic Plug:

1. It is formed when the lava solidifies in the volcanic neck.
2. The surrounding rock material is removed by different agents of erosion; the vent stands predominantly. It is called as volcanic plug.
3. The diameter of a plug varies between 300 and 600 metres.
4. The Devil’s Tower in Wyoming, United State of America is the best example.

Cinder Cone:

1. Solid material is ejected in large quantity.
2. This material consists of ash, cinder and breccias.
3. Cinders are half burnt pieces of solid material.
4. The solid material is deposited around the mouth until a conical hill with steep slopes is formed.
5. For example, cone of Mt. Nuovo in Italy.

Composite Cone:

1. Composite cones are built up of alternate layers of lava and cinder.
2. This cone is composed of two materials and therefore it is called a composite cone.
3. It is symmetrical in shape.
4. For example, Mt. St. Helens, USA.

Question 6.
Volcanic Materials
Answer:
There are three main types of material which come out in volcanic eruptions namely liquid, solid and gaseous form.
Liquid material:

1. It is the molten rock material. When the molten rock material is below the earth’s surface, it is called ‘Magma’.
2. When it appears on the surface it is called ‘lava’. On the basic of percentage of silica, it is classified as:

Acidic lava:

1. It contains higher percentage of silica.
2. It has high melting point.
3. It is thick, fluid and moves slowly.

Basic lava:

1. It contains less percentage of silica.
2. It has low melting point.
3. It’s thicker, fluid and can flow over longer distance.

Solid material:

1. It consists of dust particles and rock fragments.
2. When the material is very fine, it is called volcanic dust.
3. The small sized solid particles are called ash.
4. The solid angular fragments are known breccias.
5. Sometimes, the lava material thrown into the air solidifies into small fragments before falling on the earth’s surface; it is called volcanic bombs.

Gaseous material:

1. At the time of volcanic eruption, a dark cloud of smoke can be seen over the crater.
2. On the basis of shape, cloud is called cauliflower cloud.
3. Various inflammable gases are found in these clouds.
4. These gases produce flames.

Question 7.
Shadow Cone
Answer:

1. The waves which are caused by earthquake are called seismic waves. There are three types of waves: P-waves, S-waves and longitudinal waves.
2. P- waves can pass through all the mediums while S-waves can pass only through solid medium.
3. Even though P-waves pass through all mediums, they experience refraction as they pass from one medium to the other.
4. However, there exist some specific areas where the waves of that earthquake are not reported. Such zones are called ‘shadow zones’.
5. Generally, seismographs located at any distance within 105° from the epicentre, record both P-waves and S-waves. However, beyond 140° P-waves are recorded but not S-waves.
6. Thus, the zone between 105° and 140° is identified as the shadow zone for both types of waves.
7. The entire zone beyond 105° does not receive S-waves. The shadow zone of S-waves is much larger than that of P-waves.
8. The shadow zone of P-waves appears as a band around the earth between 105° and 140° away from the epicentre.

Draw a neat and labelled diagram for

Question 1.
Parts of fold
Answer:

Question 2.
Block Mountain
Answer:

Question 3.
Rift Valley
Answer:

Answer in detail.

Question 1.
Give the distribution of earthquakes and volcanic belts in the world.
Answer:
There are three major belts or zones of earthquakes and volcanoes on the earth.
Circum-Pacific belt:

1. This belt is also called as ‘Ring of Fire’ as it has maximum number of active volcanoes.
2. It includes the volcanoes of eastern and western coastal areas of the Pacific Ocean.
3. This belt contains most of the world-famous volcanic mountains and volcanic cones.
4. The highest volcanic mountain of the world Cotopaxi is located in this belt.
5. Fujiyama (Japan) Mt. St. Helens (Washington, USA) Pinatubo and Mayon (Philippines) are other significant volcanoes in this belt.

Mid-Atlantic belt:

1. This belt covers the volcanoes mainly along the Mid-Atlantic ridge.
2. The most active volcanic area in Mid-Atlantic ridge is Iceland.

Mid-Continental belt:

1. This belt includes the volcanoes of Alpine mountain chains, the Mediterranean Sea and volcanoes of fault zone of Eastern Africa.
2. The famous volcanoes in this belt are Stromboli and Mt. Etna.

Question 2.
Explain different types of folds.
Answer:
Folding occurs when compressional forces are applied to rocks which are ductile or flexible. The different types of folds are.
Symmetrical folds:

1. The axial plane is vertical.
2. The limbs are inclined at the same angle.

Asymmetrical folds:

1. The axial plane is inclined.
2. The limbs are inclined at different angles.

Overturned fold:

1. One limb lies above the other limb.
2. Limbs slope unequally in the same direction.

Recumbent fold:

1. One Axial plane is almost horizontal.
2. One limb lies over the other in horizontal direction.

Isoclinal fold:

1. The limbs slope in the same direction with same amount.
2. The axial plane may be vertical, inclined or horizontal.
3. Slope of some portion of limbs is near vertical.

Question 3.
Explain different types of slow movements.
Answer:
Slow movement can be classified as:
Vertical or Epeirogenic Movements:

1. Slow movements keep on taking place either towards the centre of the earth or away from it towards the crust.
2. Due to such movements, an extensive portion of the crust is either raised up or it subsides.
3. When a portion of the crust is raised up above sea level, it leads to formation of continents. Hence, they are also called ‘continent-building movements.’
4. Such movement can also form extensive plateaus.
5. These movements are not related to development of tensions or pressure in the earth’s crust.

Horizontal or Orogenic Movements:

1. These movements work in horizontal direction.
2. These movements produce compression or tension in the rock strata.
3. These movements lead to either folds or cracks in the surface of the earth. These movements give rise to mountains.
4. Their speed is more than ‘continental-building’ movements.
5. These movements either produce folds or faults. Consequently, either fold mountains or block mountains are formed.

Balbharti Maharashtra State Board 12th Biology Important Questions Chapter 4 Molecular Basis of Inheritance Important Questions and Answers.

Maharashtra State Board 12th Biology Important Questions Chapter 4 Molecular Basis of Inheritance

Multiple Choice Questions

Question 1.
How many of the following characteristics are shown by the R-strain of Streptococcus pneumonia? Avirulent, Smooth, Pathogenic, Capsulated ………………..
(a) One
(b) TWo
(c) Three
(d) Four
Answer:
(a) One

Question 2.
Griffith obtained …………….. from the blood of the dead mice.
(a) dead S-strain bacteria
(b) live R-strain bacteria
(c) dead R-strain bacteria
(d) live S-strain bacteria
Answer:
(d) live S-strain bacteria

Question 3.
Oswald T. Avery, Colin M. MacLeod and Maclyn McCarty demonstrated that ………………..
(a) transformation of live S-strain bacteria into R-strain type was because of DNA of bacteria of S-strain.
(b) the transforming substance was either a protein or RNA.
(c) only DNA was able to transform harmless R-strain into virulent S-strain.
(d) when DNA isolated from S-strain bacteria, was digested with DNase, the transformation occurred.
Answer:
(c) only DNA was able to transform harmless R-strain into virulent S-strain

Question 4.
Which of the following was NOT observed in Hershey and Chase experiment?
(a) Viruses grown in the presence of radioactive sulphur, had radioactive protein but not radioactive DNA.
(b) Radioactive ‘P’ remained in suspension.
(c) Only radioactive ‘P’ was found inside the bacterial cells in the pellet.
(d) Viruses grown in the presence of radioactive phosphorus contained radioactive DNA but not radioactive proteins.
Answer:
(b) Radioactive ‘P’ remained in suspension.

Question 5.
Enzymes like ……………….. and DNA topoisomerase-I, play important role in maintaining super-coiled state in prokaryotic DNA.
(a) DNA ligase
(b) DNA gyrase
(c) RNA polymerase
(d) None of these
Answer:
(b) DNA gyrase

Question 6.
Histone octamer of nucleosome has two molecules, each of ……………….. proteins.
(a) H₂A, H₂B, H₃ and H₄
(b) H₂A, H₂B, H₃ and H₁
(c) H₂A, H₂B. H₃A and H₃B
(d) H₁A, H₂B, H₃A and H₄
Answer:
(a) H₂A, H₂B, H₃ and H₄

Question 7.
Select the CORRECT statement.
(a) Euchromatin is mainly located near centromere and telomeres.
(b) Heterochromatin replicates at faster rate than euchromatin.
(c) Heterochromatin has 2 to 3 times more DNA than in the euchromatin.
(d) Heterochromatin is lightly stained region of chromonema.
Answer:
(c) Heterochromatin has 2 to 3 times more DNA than in the euchromatin

Question 8.
A DNA molecule in which both strands have 14N is allowed to replicate in an environment containing ¹⁵N. What will be the exact number of DNA molecules that contain the ¹⁴N after three replications?
(a) One
(b) Two
(c) Four
(d) Eight
Answer:
(b) Two

Question 9.
As the base sequence present on one strand of DNA decides the base sequence of other 8 strand, this strand is considered as ………………..
(a) descending strand
(b) leading strand
(c) lagging strand
(d) complementary strand
Answer:
(d) complementary strand

Question 10.
In prokaryotes ……………….. recognizes the promoter sequence.
(a) alpha factor
(b) rho factor
(c) theta factor
(d) sigma factor
Answer:
(d) sigma factor

Question 11.
If the base sequence in DNA is 5′ AAAA 3′, then the base sequence in m-RNA is ………………..
(a) 5′ UUUU 3′
(b) 3′ UUUU 5′
(c) 5′ AAAA 3′
(d) 3′ TTTT 5′
Answer:
(c) 5′ AAAA 3′

Question 12.
During capping, methylated guanosine tri¬phosphate is added to 5′ end of ………………..
(a) m-RNA
(b) t-RNA
(c) hnRNA
(d) r-RNA
Answer:
(c) hnRNA

Question 13.
If each codon has two nucleotides, then there will be ……………….. codons, which can encode for only …………….. different types of amino acids.
(a) 16, 16
(b) 16, 20
(c) 20, 16
(d) 64, 64
Answer:
(a) 16, 16

Question 14.
What would happen if in a gene encoding a polypeptide of 50 amino acids, 25th codon (UAU) is mutated to UAA?
(a) A polypeptide of 24 amino acids is formed.
(b) Two polypeptides of 24 and 25 amino acids will be formed.
(c) A polypeptide of 49 amino acids is formed.
(d) A polypeptide of 25 amino acids is formed.
Answer:
(a) A polypeptide of 24 amino acids is formed.

Question 15.
A strand of DNA has following base sequence – 3′ AAAAGTGAATAGTGA 5′. On transcription it produces an m-RNA. Which of the following anticodon of t-RNA recognizes the third codon of this m-RNA?
(a) AAA
(b) CUG
(c) AAG
(d) CTG
Answer:
(c) AAG

Question 16.
Polynucleotide chain consisting of only CUA repeats will give polypeptide chain with only one amino acid ………………..
(a) tryptophan
(b) leucine
(c) serine
(d) methionine
Answer:
(b) leucine

Question 17.
Select the INCORRECT statement.
(a) Dr. Khorana prepared polyribo-nucleotides chains with known repeated sequences of two or three nucleotides by using synthetic DNA.
(b) M. Nirenberg and Matthaei synthesized artificial m-RNA which was a homopolymer of uracil ribonucleotides.
(c) Enzyme polynucleotide phosphorylase polymerizes RNA with defined sequences in a template-dependent manner.
(d) Evidence for triplet nature of geneticcode, was given by Crick (1961) using “frame-shift mutation”.
Answer:
(c) Enzyme polynucleotide phosphorylase polymerizes RNA with defined sequences in a template-dependent manner.

Question 18.
…………… is/are based on complementarity principle.
(a) Replication and translation
(b) Replication and transcription
(c) Translation
(d) Only replication
Answer:
(b) Replication and transcription

Question 19.
Cysteine has codons, while isoleucin has ……………….. codons.
(a) two, three
(b) three, two
(c) two, four
(d) four, two
Answer:
(a) two, three

Question 20.
Out of 64 codons, only 61 code for the 20 different amino acids. This is known as ……………….. of genetic code.
(a) non-ambiguity
(b) overlapping nature
(c) ambiguity
(d) degeneracy
Answer:
(d) degeneracy

Question 21.
Mutation that results in Sickle-cell anaemia is a ………………..
(a) deletion
(b) frame-shiftmutation
(c) point mutation
(d) insertion
Answer:
(c) point mutation

Question 22.
Initiator charged t-RNA occupies the ……………….. of ribosome first.
(a) A-site
(b) P-site
(c) E-site
(d) either A-site or P-site
Answer:
(b) P-site

Question 23.
It takes ……………….. for formation of peptide bond.
(a) 10 seconds
(b) 0.1 second
(c) less than 0.1 second
(d) 60 seconds
Answer:
(c) less than 0.1 second

Question 24.
Anticodon and codon bind by ………………..
(a) glycosidic bond
(b) hydrogen bond
(c) phosphodiester bond
(d) none of these
Answer:
(b) hydrogen bond

Question 25.
The UTRs are present at ………………..
(a) 5′-end, before start codon and at 3′-end, after stop codon of m-RNA
(b) 5′-end, before start codon and at 3′-end, after stop codon of t-RNA
(c) only at 3′-end, after stop codon of m -RNA
(d) only at 5′-end, before start codon of m-RNA
Answer:
(a) 5′-end, before start codon and at 3′-end, after stop codon of m-RNA

Question 26.
The action of structural genes is regulated by …………….. site with the help of a …………….. protein.
(a) operator, inducer
(b) operator, repressor
(c) regulator, repressor
(d) regulator, inducer
Answer:
(b) operator, repressor

Question 27.
Repressor protein is produced by the action of ………………..
(a) gene z
(b) gene y
(c) gene i
(d) gene o
Answer:
(c) gene i

Question 28.
Select the correct pair.
(a) Gene z – Transacetylase
(b) Gene y – Beta-galactocidase
(c) Gene a – Beta-galactoside permease
(d) Gene I – Repressor
Answer:
(d) gene I – repressor

Question 29.
Structural genomics involves ……………….. of genome.
(a) mapping
(b) sequencing
(c) analysis
(d) all of these
Answer:
(d) all of these

Question 30.
The technique of transferring DNA fragments separated on agarose gel to a synthetic nitrocellulose membrane is known as ………………..
(a) Southern blotting
(b) Autoradiography
(c) Southern hybridization
(d) None of these
Answer:
(a) Southern blotting

Question 31.
Sequence of various steps in DNA fingerprinting is ………………..
i. Southern blotting.
ii. Restriction digestion
iii. Agarose gel electrophoresis
iv. DNA isolation
v. Photography.
vi. Selection of DNA probe
vii. Hybridization
(a) iv, iii, ii, i, v, vi, vii
(b) iv. v, iii, i, vi, vii, ii
(c) iv, ii, iii, i, vi, vii, v
(d) ii, iii, iv, i, vi, vii,
Answer:
(c) iv, ii, iii, i, vi. vii, v

Match the Columns

Question 1.

Column A	Column B
(1) Frederick Griffith	(a) Test tube assay
(2) Avery, McCarty and MacLeod	(b) Streptococcus pneumoniae
(3) Alfred Hershey and Martha Chase	(c) E. coli
(4) Meselson and Stahl	(d) Bacteriophages

Answer:

Column A	Column B
(1) Frederick Griffith	(b) Streptococcus pneumoniae
(2) Avery, McCarty and MacLeod	(a) Test tube assay
(3) Alfred Hershey and Martha Chase	(d) Bacteriophages
(4) Meselson and Stahl	(c) E. coli

Classify the following to form Column B as per the category given in Column A

Question 1.
(i) UUU
(ii) CUA
(iii) UAA
(iv) AUG
(v) UAG
(vi) UGA

Column A	Column B
1. Initiator codon	————–
2. Stop codons	————-
3. Codon that codes for Phenyl alanin	————–
4. Codon that codes for leucine	————-

Answer:

Column A	Column B
1. Initiator codon	(iv) AUG
2. Stop codons	(iii) UAA, (v) UAG, (vi) UGA
3. Codon that codes for Phenyl alanin	(i) UUU
4. Codon that codes for leucine	(ii) CUA

Question 2.
(i) Severo Ochoa
(ii) F. Jacob and J. Monod
(iii) Temin and Baltimore
(iv) H. Winkler
(v) T. H. Roderick
(vi) R Kornberg

Column A	Column B
(1) Lac Operon	————–
(2) Central dogma in retroviruses	————-
(3) Coined the term Genome	————–
(4) Coined the term Genomics	————-
(5) Enzymatic synthesis of RNA	————-
(6) DNA is associated with histones and non-histones	————–

Answer:

Column A	Column B
(1) Lac Operon	(ii) E Jacob and J. Monod
(2) Central dogma in retroviruses	(iii) Temin and Baltimore
(3) Coined the term Genome	(iv) H. Winkler
(4) Coined the term Genomics	(v) T. H. Roderick
(5) Enzymatic synthesis of RNA	(i) Severo Ochoa
(6) DNA is associated with histones and non-histones	(vi) R. Kornberg

Very Short Answer Questions

Question 1.
What are the two types of bacteria used by F. Griffith and which one out of these is avirulent?
Answer:
S-type and R-type strains of Streptococcus penumoniae were used by F. Griffith and out of these R-type is avirulent.

Question 2.
Enlist the characteristics of S-strain pneumoniae.
Answer:
S-strain pneumoniae are virulent, smooth and encapsulated.

Question 3.
What is the bacteriophage?
Answer:
Bacteriophage is a virus that infects bacterium and injects its genetic material in the bacterium.

Question 4.
What is the length of DNA double helix molecule in a typical mammalian cell?
Answer:
The length of DNA double helix molecule in a typical mammalian cell is approximately 2.2 meters.

Question 5.
What is the approximate size of a typical nucleus ?
Answer:
Approximate size of a typical nucleus is 10^-6 m.

Question 6.
What is size of E. coli cell?
Answer:
The size of E. coli cell size is 2-3 µm.

Question 7.
What determines the charge on protein molecules?
Answer:
A protein acquires its charge depending upon the abundance of amino acid residues with charged side chains.

Question 8.
What is nucleosome core?
Answer:
Nucleosome core is a histone octamer.

Question 9.
Where is H₁ histone present?
Answer:
H₁ histone binds the DNA thread where it enters and leaves the nucleosome.

Question 10.
How are solenoid fibres formed?
Answer:
Six nucleosomes get coiled and then form solenoid that looks like coiled telephone wire of 30 nm diameter (300Å).

Question 11.
How is chromatin fibre formed?
Answer:
Supercoiling of solenoid fibre forms a looped structure called chromatin fibre.

Question 12.
What is NHC?
Answer:
NHC stands for Nonhistone Chromosomal proteins.

Question 13.
List as many different enzyme activities required during DNA synthesis as you can.
Answer:
Phosphorylase, Helicase, DNA polymerase, Primase, DNA ligase, Super helix relaxing enzyme, Topoisomerase (gyrase) are different enzymes required during DNA synthesis.

Question 14.
How many replicons are present in prokaryotes and eukaryotes respectively?
Answer:
Prokaryotes have one replicon. Several replicons in tandem are present in eukaryotes.

Question 15.
What is the function of SSBP?
Answer:
During replication of DNA SSBP proteins remain attached to both the separated strands and prevent them from coiling back.

Question 16.
During which phases of cell cycle, transcription occurs in the nucleus?
Answer:
Transcription occurs in the nucleus during G₁ and G₂ phases of cell cycle.

Question 17.
Which strand of transcription unit gets transcribed ?
Answer:
DNA strand having 3’ → 5’ polarity acts as template strand and it gets transcribed.

Question 18.
What is a cryptogram?
Answer:
Cryptogram is a genetic code consisting of triplet codons on m-RNA that code for a specific amino acids.

Question 19.
What is meant by the polarity of genetic code?
Answer:
Genetic code is always read in 5′ → 3’ direction. This is called polarity of genetic code.

Question 20.
Which mutation can result in changes in the reading frame?
Answer:
Insertion or deletion of one or two bases changes the reading frame from the point of insertion or deletion.

Question 21.
Which mutation can result in insertion or deletion of amino acids, but reading frame remains unaltered?
Answer:
Insertion or deletion of three or multiples of three bases results in insertion or deletion of amino acids and reading frame remains unaltered from that point onwards.

Question 22.
Which molecule serves as an intermediate molecules between DNA and protein during proteins synthesis?
Answer:
RNA serves as an intermediate molecule between DNA and protein during proteins synthesis.

Question 23.
What is the function of a groove present between two subunits of ribosome in eukaryotes ?
Answer:
The groove present between two subunits of ribosomes in eukaryotes protects the polypeptide chain from the action of cellular enzymes and also protects m-RNA from the action of nucleases.

Question 24.
Enlist different steps of protein synthesis.
Answer:
Steps in protein synthesis are:

1. Transcription
2. Activation of amino acids and formation of charged t-RNAs,
3. Synthesis of polypeptide chain:
4. initiation
5. elongation and
6. termination of polypeptide chain.

Question 25.
What is translocation?
Answer:
During elongation of polypeptide chain, the ribosome moves along the m-RNA in stepwise manner from start codon to stop codon (5′ → 3′), 1 codon ahead each time t, his movement is called translocation and due to this t-RNA carrying a dipeptide at A-site of the ribosome moves to the p-site.

Question 26.
What is meant by inducible enzymes?
Answer:
Bacteria like E.coli adapt to their chemical environment by synthesizing certain enzymes depending upon the substrate present. Such adaptive enzyme is called inducible enzyme.

Question 27.
What is meant by induction and inducer?
Answer:
A set of genes are switched on when a new substrate is to be metabolized. This phenomenon is called induction and small molecule responsible for this is known as inducer.

Question 28.
What is the role of a repressor gene?
Answer:
The role of a repressor gene is to produce repressor protein. Repressor binds with operator gene and this prevents transcription of structural genes in the operon.

Question 29.
Which molecule does act as inducer molecule in lac operon?
Answer:
Allolactose acts as inducer molecule in lac operon.

Question 30.
In which condition, lac operon is switched off?
Answer:
If E.coli bacteria do not have lactose in the surrounding medium as a source of energy, lac operon is switched off.

Question 31.
What lac operon consists of?
Answer:
Lac operon consists of a regulator promoter, operator and three structural genes z, y and a.

Question 32.
Which gene acts as a regulatory gene in lac operon?
Answer:
Repressor protein is produced by the action of gene i (inhibitor). This gene acts as a regulator gene.

Question 33.
When was Human Genome Project started ? When was it completed ?
Answer:
The Human Genome Project was started in 1990 and was completed in 2003.

Question 34.
What is functional genomics?
Answer:
Functional genomics is a branch of genomics that involves the study of functions of all gene sequences and their expressions in organisms.

Question 35.
What is the advantage of sequencing of genomes of non-human organisms?
Answer:
Sequencing of genomes of non-human model organisms allows researchers to study gene functions in these organisms. Since human beings possess many genes which are like those of flies, roundworms and mice, comparative studies will lead to greater understanding of human evolution.

Question 36.
What are VNTRs?
Answer:
Variable Number of Tandem Repeats (VNTRs) are unusual sequences of 20-100 base pairs, which are repeated several times and are arranged tandency.

Question 37.
Do different organisms have the same DNA?
Answer:
Different organisms differ in their DNA sequence.

Question 38.
What is the amino acid sequence encoded by base sequence UCA, UUU, UCC, GGG, AGU of an m-RNA segment?
Answer:
The amino acid sequence: Ser-Phe – Ser – Gly- Ser

Give definitions of the following

Question 1.
Replicon
Answer:
The unit of DNA in which replication occurs is known as replicon.

Question 2.
Transcription
Answer:
Transcription is defined as the process of copying of genetic information from template strand of DNA into a complementary single stranded RNA transcript.

Question 3.
Gene
Answer:
Gene is defined as the DNA sequence coding for m-RNA/ t-RNA or r-RNA.

Question 4.
Cistron
Answer:
Cistron is defined as a segment of DNA coding for a polypeptide.

Question 5.
Monocistronic gene
Answer:
Gene is called monocistronic, when there is a single structural gene in one transcription unit.

Question 6.
Polycistronic gene
Answer:
Gene is called polycistronic, when there is a set of various structural genes in one transcription unit.

Question 7.
Interrupted or Split genes
Answer:
Interrupted or split genes are the structural genes in eukaryotes which have both exons and introns.

Question 8.
Exons
Answer:
Exons are the coding sequences or express sequences in DNA/hnRNA/ m-RNA.

Question 9.
Introns
Answer:
Introns are the non-coding sequences in DNA or hnRNA.

Question 10.
Anticodon
Answer:
Anticodon is a triplet of nucleotides present on the anticodon loop of t-RNA, which is complementary to codon on m-RNA.

Question 11.
Mutation
Answer:
Mutation is a sudden heritable change in the DNA sequence that results in the change of genotype.

Question 12.
Translation
Answer:
Translation is the process in which sequence of codons of m-RNA is decoded and accordingly amino acids are added in specific sequence to form a polypeptide on ribosomes.

Question 13.
Genomics
Genomics is the study of genomes through analysis, sequencing and mapping of genes along with the study of their functions.

Question 14.
Repressors
Answer:
Repressors are proteins which are able to bind the operator region of operon and prevent the RNA polymerase from transcribing the operon.

Name the following

Question 1.
Enzyme that cleaves DNA.
Answer:
DNase

Question 2.
Enzyme that cleaves proteins.
Answer:
Protease

Question 3.
Enzyme involved in activation of nucleotides.
Answer:
Phosphorylase

Question 4.
Enzyme involved in unwinding of DNA.
Answer:
Helicase

Question 5.
Enzyme involved in synthesis of DNA.
Answer:
DNA polymerase

Question 6.
Enzyme involved in joining of Okazaki fragments.
Answer:
DNA ligase

Question 7.
Enzyme involved in synthesis of RNA primer.
Answer:
Primase

Question 8.
Enzyme involved in removal of RNA primer.
Answer:
DNA polymerase

Question 9.
Enzyme involved in replacement of gaps in prokaryotes.
Answer:
DNA polymerase – I

Question 10.
Enzyme involved in replacement of gaps in eukaryotes.
Answer:
DNA polymerase α

Question 11.
Enzyme involved in formation of double helix in daughter DNA molecules.
Answer:
Topoisomerase

Question 12.
Enzyme involved in releasing strain created by unwinding of DNA.
Answer:
Super helix relaxing enzyme

Question 13.
Enzyme involved in synthesis of hnRNA, m-RNA.
Answer:
RNA polymerase – II

Question 14.
Enzyme involved in synthesis of t-RNA, snRNA.
Answer:
RNA polymerase – III

Question 15.
Enzyme involved in synthesis of r-RNA
Answer:
RNA polymerase – I

Question 16.
Enzyme involved in polymerizing RNA in template independent manner.
Answer:
Polynucleotide phosphorylase

Question 17.
Enzyme involved in peptide bond synthesis.
Answer:
Ribozyme

Question 18.
Enzyme involved in Cutting DNA at specific sites.
Answer:
Restriction endonuclease

Question 19.
Name the initiator codon of protein synthesis.
Answer:
AUG is the initiator codon of protein synthesis.

Question 20.
Name three binding sites of ribosome.
Answer:
Three binding sites for t-RNA on ribosomes are P-site (peptidy t-RNA-site), A-site (aminoacyl – t-RNA-site) and E-site (exit site).

Question 21.
Name the different structural genes in sequence of lac operon.
Answer:
There are 3 structural genes in the sequence lac-Z, lac-Y and lac-A.

Question 22.
Name the organisms whose genomes have been sequenced?
Answer:
The genomes of several organisms such as bacteria e.g. E.coli, Caenorhabditis elegans (a free living non-pathogenic nematode), Saccharomyces cerevisiae (yeast), Drosophila (fruit fly), plants (rice and Arabidopsis), Mus musculus (mouse), etc. have been sequenced.

Give Significance/Functions of the following

Question 1.
DNA.
Answer:

1. DNA regulates and controls all the cellular activities.
2. It replicates and gets distributed equally to the daughter cells when the cell divides.
3. It is a carrier of genetic information.
4. Heterocatalytic function : DNA directs the synthesis of chemical molecules other than itself. E.g. Synthesis of RNA (transcription), synthesis of protein (Translation), etc.
5. Autocatalytic function : DNA directs the synthesis of DNA itself. E.g. Replication.
6. DNA is a master molecule of a cell that initiates, guides, regulates and controls the process of protein synthesis.

Question 2.
Proteins.
Answer:
Proteins serve as structural components, enzymes and hormones.

Distinguish between the following.

Question 1.
Euchromatin and Heterochromatin.
Answer:

Euchromatin	Heterochromatin.
1. Euchromatin is loosely packed region of the chromatain.	1. Heterochromatin is densely packed region of the chromatin.
2. Euchromatin stains lightly.	2. Heterochromatin stains darkly.
3. Euchromatin is transcriptionally active region of the chromatin.	3. Heterochromatin is transcriptionally inactive region of the chromatin.

Question 2.
DNA in prokaryotic and eukaryotic cells.
Answer:

DNA in prokaryotes	DNA in eukaryotic
1. It is present in the cytoplasm.	1. It is present in the nucleus.
2. It is not associated with histones.	2. It is associated with histones.
3. It is circular.	3. It is linear.
4. Genes do not contain introns.	4. Genes contain introns along with exons.
5. Genes are polycostronic.	5. Genes are monocistronic.

Question 3.
DNA and RNA
Answer:

DNA	RNA
1. DNA is deoxyribonucleic acid.	1. RNA is ribonucleic acid.
2. DNA is double stranded, helical molecule.	2. RNA is single stranded molecule.
3. In DNA, there is deoxyribose sugar.	3. In RNA, there is ribose sugar.
4. The pyrimidine nitrogen bases are cytosine and thymine.	4. The pyrimidine nitrogen bases are cytosine and uracil.
5. DNA is the genetic material in all types of organisms.	5. RNA is genetic material in few viruses only.
6. In eukaryotic cells, DNA is present in nucleus.	6. In eukaryotic cells, RNA is present in nucleus as well as cytoplasm.
7. The number of purine : pyrimidine ratio is always 1 : 1 in DNA molecule.	7. The number of purine : pyrimidine ratio may not be 1 : 1 in RNA molecule.
8. DNA sends the codon for the synthesis of proteins, but otherwise it does not participate in the protein synthesis.	8. RNA takes part in the protein synthesis through transcription and translation.

Question 4.
m-RNA, t-RNA and r-RNA.
Answer:

m-RNA	t-RNA	r-RNA.
1. m-RNA is a simple molecule which shows linear structure without any folds.	1. t-RNA is a single stranded molecule. There is regular pattern of folding shown by this molecule.	1. r-RNA is a single stranded RNA that is variously folded upon itself. In the folded regions it shows complementary base pairing.
2. It performs the function of transcription during protein synthesis.	2. It performs the function of transferring the amino acids during translation.	2. This RNA remains associated with the ribosomes permanently. It gives the binding site for m-RNA during the process of protein synthesis. It also orients the m-RNA molecule so as to read the message on codons properly.
3. Of the total cellular RNA, m-RNA forms 3-5%.	3. Of the total cellular RNA, t-RNA forms about 10-20%.	3. Of the total cellular RNA, r-RNA forms 80%
4. It has molecular weight of about 5,00,000.	4. t-RNA is the smallest RNA having only 73-93 nucleotides and has molecular weight of about 23,000 to 30,000 daltons.	4. Molecular weight is about 40,000 to 100,000 daltons.

Give Reasons

Question 1.
Nuclein was called as nucleic acid.
Answer:
Nuclein had acidic properties and it was isolated from nucleus. Hence, it was called as nucleic acid.

Question 2.
Initially proteins (and not DNA) were considered as genetic material.
Answer:

1. Proteins are large, complex molecules and store information required to govern cell metabolism. Hence it was assumed that variations found in species were caused by proteins.
2. On the other hand, DNA was considered as a small, simple molecule whose composition does not vary much among species.
3. Variations in the DNA molecules are different than the variation in shape, electrical charge and function shown by proteins.
4. Hence, initially proteins (and not DNA) were considered as genetic material.

Question 3.
On injecting a mixture of heat-killed S-bacteria and live R bacteria, the mice died.
Answer:

1. Griffith obtained live S-strain bacteria from the blood of the dead mice.
2. In a mixture of live R-bacteria and heat killed S-bacteria, live R-strain bacteria picked up something (transforming principle) from the heat-killed S bacterium and got changed into S-type.
3. Transforming principle allowed R-type bacteria to synthesize capsule and thus they became virulent.
4. Hence, on injecting a mixture of heat-killed S bacteria and live R bacteria, the mice died.

Question 4.
Viruses obtained by infecting bacteria having radioactive phosphorus contained radioactive DNA (labelled DNA), but not radioactive proteins.
Answer:
Viruses obtained by infecting bacteria having radioactive phosphorus, contained radioactive DNA (labelled DNA). but not radioactive proteins because DNA contains phosphorus (labelled DNA) but proteins do not.

Question 5.
Viruses obtained by infecting bacteria having radioactive sulphur contained radioactive protein but not radioactive DNA.
Answer:
Viruses obtained by infecting bacteria having radioactive sulphur contained radioactive protein but not radioactive DNA because DNA does not contain sulphur and proteins contain sulphur.

Question 6.
In bacteria, m-RNA does not require any processing.
Answer:
In bacteria, m-RNA does not require any processing because it has no introns and it is synthesized in cytoplasm.

Question 7.
Eukaryotic DNA is condensed and supercoiled.
Answer:

1. In a typical mammalian cell, length of DNA double helix is approximately 2.2 metres.
2. The size of typical nucleus is approximately 10^-6 m
3. Such a long DNA molecule has to be fitted in small nuclear space.
4. Therefore, DNA is highly condensed, coiled and supercoiled so that it can be accommodated in the nucleus.

Question 8.
During translation, complementarity principle is not applicable.
Answer:
During translation, complementarity principle is not applicable as, genetic information is transferred from a polymer of nucleotides to a polymer of amino acids.

Question 9.
Protein synthesis is the most important and essential activity in the living cells.
Answer:

1. Proteins play a significant role in the metabolism of living cells.
2. The actual phenotypic expression of living cells is dependent on the biochemical reactions.
3. Each biochemical reaction needs a specific enzyme for its initiation and completion. All the enzymes are proteins.
4. In a cell there are many structural proteins too. Thousands of structural and catalytic proteins are constantly required within the cell at all times.
5. Many functional proteins like hormones are also important for metabolism. Thus, for the synthesis of all such proteins, protein synthesis has become the most important and essential activity of the living cell.

Question 10.
Only 20 amino acids are considered as standard.
Answer:

1. It was believed that there are total 20 amino acids in the living world. But 21st amino acid called selenocysteine was discovered later.
2. This amino acid is coded by UGA which is usually a termination codon.
3. In both prokaryotic and eukaryotic cells polypeptide chains contain 100-300 amino acids and they are formed by specific arrangement of 21 amino acids.
4. But formation of selenocysteine requires the availability of element selenium in the cells.
5. Therefore, only 20 amino acids are considered as standard.

Write Short Notes on the following

Question 1.
Friedrich Miescher’s nuclein
Answer:

1. Nuclein is an acidic substance, having high phosphorus content and it was isolated by Friedrich Miescher in 1869, from the nuclei of pus cells.
2. As Nuclein had acidic properties and it was isolated from nucleus, it was called as nucleic acid.
3. E Miescher started working with white blood cells (the major component of pus). He used a salt solution to wash the pus off the bandages. He lysed the cells by adding a weak alkaline solution and isolated nucleic acid from nuclei that precipitated out of the solution.
4. By the early 1900s, it was known that Miescher’s nuclein was a mixture of proteins and nucleic acids (DNA and RNA).

Question 2.
Packaging in Prokaryotes
Answer:

1. Size of cell in E. coli size is 2-3µ.
2. The nucleoid is small, circular, highly folded, naked DNA (1100 µm long in perimeter and contains about 4.6 million base pairs).
3. When the negatively charged DNA becomes circular, the size reduces to 350 µm in diameter.
4. Folding/looping (40-50 domains (loops) further reduce it to 30 µm in diameter.
5. RNA connectors assist in loop formation.
6. Further coiling and super coiling of each domain reduces the size to 2 µm in diameter.
7. This coiling (packaging) is assisted by positively charged HU (Histone like DNA binding proteins) proteins and enzymes like DNA gyrase and DNA topoisomerase-I, which maintain supercoiled state.

Question 3.
Experimental confirmation of semiconservative replication of DNA.
Answer:

(1) Matthew Meselson and Franklin Stahl (1958) used equilibrium – density – gradient – centrifugation technique to experimentally prove semiconservative DNA replication.

(2) They cultured bacteria E.coli in the medium containing ¹⁴N (light nitrogen). They obtained equilibrium density gradient band by using 6M CsCl₂. The position of this band is recorded.

(3) E. coli cells were then transferred to ¹⁵N medium (heavy isotopic nitrogen) and allowed to replicate for several generations. At equilibrium point density gradient band was obtained, by using 6M CsCl₂. The position of this band is recorded.

(4) The heavy DNA (¹⁵N) molecule can be distinguished from normal DNA by centrifugation in a 6M Cesium chloride (CsCl₂) density gradient. At the equilibrium point ¹⁵N DNA will form a band. In this both the strands of DNA are labelled with ¹⁵N.

(5) Such E. coli cells were then transferred to another medium containing ¹⁴N i.e. normal (light) nitrogen. After first generation, the density gradient band for ¹⁴N ¹⁵N was obtained and its position was recorded. After second generation, two density gradient bands were obtained – one at ¹⁴N ¹⁵N position and other at ¹⁴N position.

(6) The position of bands after two generations clearly proved that DNA replication is semiconservative.

Question 4.
Central Dogma of molecular biology.
Answer:
(1) Central dogma of molecular biology was postulated by EH.C. Crick in 1958.

(2) DNA gets transcribe to form m-RNA, m-RNA acts as a messenger and gets translated to form a polypeptide chain (protein) having specific amino acid sequence.

(3) This unidirectional flow of information from DNA to RNA and from RNA to proteins is referred as central dogma of molecular biology.

(4) Temin (1970) and Baltimore (1970) : Central dogma in retroviruses.

Question 5.
Processing of hnRNA.
Answer:

1. Eukaryotes have split genes.
2. Primary transcript or hnRNA is non-functional and contains both exons and introns.
3. Processing of hnRNA results in functional m-RNA.
4. The fully processed hnRNA is called m-RNA.
5. m-RNA comes out of the nucleus through nuclear pore for getting translated.

hnRNA undergoes capping, tailing and splicing.

1. Capping : Methylated guanosine tri¬phosphate is added to 5’ end of hnRNA.
2. Tailing : Polyadenylation take place at 3′ end.
3. Splicing : It is removal of introns.
4. DNA ligase joins exons in a definite sequence (order).

Question 6.
Cracking of genetic code.
Answer:

1. M. Nirenberg and Matthaei synthesized artificial poly-U m-RNA.
2. Using this synthetic poly-U m-RNA and cell free system of protein synthesis, a small polypeptide consisting of only amino acid phenylalanine was obtained.
3. It suggested that UUU codes for phenylalanine.
4. Dr. Har Gobind Khorana devised a technique for synthesis of artificial m-RNA with repeated sequences of known nucleotides.
5. He synthesized artificial RNA consisting of known repeated sequences of two or three nucleotides. E.g. CUC, UCU, CUC, UCU, by using synthetic DNA.
6. This resulted in formation of polypeptide chain consisting of alternate amino acids leucine and serine.
7. Synthetic RNA consisting of CUA, CUA, CUA, CUA repeats gave polypeptide chain with only one amino acid – leucine.
8. Severo Ochoa established that the enzyme (polynucleotide phosphorylase) also helps in polymerizing RNA of defined sequences in a template-independent manner (i.e. enzymatic synthesis of RNA).
9. Thus all the 64 codons in the dictionary of genetic code were deciphered.

Question 7.
Types of mutations.
Answer:

1. Chromosomal mutations : Loss (deletion) or gain (insertion/duplication) of a segment of DNA results in alteration in the chromosome.
2. Point mutations : They involve change in a single base pair of DNA. E.g. Mutation that results in Sickle-cell anaemia.
3. Deletion or insertion of base pairs of DNA : It causes frame-shift mutations or deletion mutation.
4. Insertion or deletion of one or two bases changes the reading frame from the point of insertion or deletion.
5. Insertion or deletion of three or multiples of three bases (insert or delete) results in insertion or deletion of amino acids and reading frame remains unaltered from that point onwards.

Question 8.
Transfer-RNA.
Answer:

(1) As t-RNA can read the codon and also can bind with the amino acid, t-RNA is considered as an adapter molecule.

(2) Clover leaf structure (2 dimensional) of t-RNA:

• t-RNA has four arms – DHU arm (has amino acyl binding loop), middle arm (has anticodon loop), Tif/C arm (has ribosome binding loop) and variable arm.
• It has G nucleotide at 5’ end.
• Amino acid acceptor end (3’ end) having unpaired CCA bases (i.e. amino acid binding site).

(3) For every amino acid, there is specific t-RNA.
(4) Initiator t-RNA is specific for methionine.
(5) There are no t-RNAs for stop codons.
(6) In the actual structure, the t-RNA molecule looks like inverted L (3 dimensional : structure)

Question 9.
UTRs.
Answer:

1. m-RNA has some additional sequences that are not translated. These sequences are referred as untranslated regions (UTR).
2. The UTRs are present at both 5′-end (before start codon) and at 3′-end (after stop codon).
3. They are required for efficient translation process.

Short Answer Questions

Question 1.
Why are Okazaki fragments formed on lagging strand only?
Answer:

1. The lagging template is the template strand with free 5’ end.
2. The replication always starts at C-3 end of template strand and proceeds towards C-5 end.
3. Both the strands of the parental DNA are antiparallel and new strands are always formed in 5′ → 3′ direction, i.e. DNA polymerase synthesizes new strand in only one direction i.e. 5′ → 3′ direction.
4. Hence, the lagging templates becomes available for replication only discontinuously in small patches.
5. The new lagging strand develops discontinuously away from the replicating fork in the form of small Okazaki fragments.
6. Hence, Okazaki fragments formed on lagging strand only.

Question 2.
Why t-RNA is called as adapter molecule?
Answer:
t-RNA can read the codon on m-RNA. It also can bind with the amino acid at 3’ end and transport it to m-RNA-ribosome complex during translation. It can bind with specific codon which is complementary to its anticodon. So t-RNA is considered as an adapter molecule.

Question 3.
Why DNA replication is called semiconservative replication?
Answer:

1. In each of the two daughter DNA molecules thus formed, one strand is parental and the other one is newly synthesized.
2. 50% is contributed by mother DNA.
3. Hence, DNA replication is described as semiconservative replication.

Question 4.
What are the functions of three types of RNAs in bacteria? Which enzyme is involved in transcription of DNA to form RNAs in bacteria? What is its function?
Answer:

1. In bacteria, m-RNA provides the encoded message for protein synthesis; t-RNA brings specific amino acid to the site of translation; r-RNA plays role in providing binding site to m-RNA and t-RNA.
2. There is single DNA dependent-RNA polymerase that catalyses transcription of all 3 types of RNA in bacteria.
3. RNA polymerase binds to promoter and initiates transcription (initiation) and synthesizes RNA.

Question 5.
Explain why it was suggested that codon is a sequence of three consecutive nucleotides on m-RNA.
Answer:

1. If each codon has only one nucleotide, then there will be 4¹ = 4 codons, which can encode for only four different types of amino acids.
2. If each codon has two nucleotides, then there will be 4² = 16 codons, which can encode for only 16 different types of amino acids.
3. If each codon has three nucleotides, then there will be 4³ = 64 codons, which are sufficient to specify 20 different types of amino acids.

Question 6.
Explain Genetic code is Non-overlapping.
Answer:

1. Each single base is a part of only one codon.
2. Adjacent codons do not overlap.
3. If it had been overlapping type, with 6 bases, there would be 4 amino acid molecules in a chain.
4. Experimental evidence favours non-overlapping nature of genetic code.

Question 7.
How degeneracy of the code is explained by Wobble hypothesis?
Answer:

1. In 1966, Crick proposed Wobble hypothesis.
2. According to this hypothesis, in codon- anticodon base pairing, the third base may not be complementary.
3. The third base of codon is called wobble base and this position is called wobble position.
4. This results in economy of t-RNA as anticodon of a t-RNA may bind with codon even when only first two bases are complementary.
5. For example, GUU, GUC, GUA and GUG codons code for amino acid Valine.
6. Degeneracy of genetic code means many codons can code for same amino acid.
7. Thus, the degeneracy of genetic code gets explained by Wobble hypothesis.

Question 8.
a. What is meant by universal genetic code? Give example.
b. Why genetic code is called Non- ambiguous?
Answer:
a. Universal genetic code means that the specific codon codes for same amino acid in all living organisms, e.g. codon AUG always specifies amino acid methionine.

b. Genetic code is called non-ambiguous because, each codon specifies a particular amino acid.

Question 9.
Give examples of termination codons. Why are they known as termination codons?
Answer:

1. UAA, UAG and UGA are known as termination codons.
2. They do not code for any amino acid.
3. They terminate or stop the process of elongation of polypeptide chain.
4. Hence, they are known as termination codons.

Question 10.
How many amino acids are required for protein synthesis? From where are they obtained?
Answer:

1. About 20 different types of amino acids are required for protein synthesis.
2. They are available in the cytoplasm.

Question 11.
How DNA regulates protein synthesis?
Answer:

1. DNA regulates protein synthesis by coding for the specific sequence of amino acids in a protein.
2. This control is possible through transcription of m-RNA.
3. Genetic code is specific for particular amino acid.

Question 12.
What is the role of ribosomes in protein synthesis?
Answer:

1. Ribosomes serve as site for protein synthesis.
2. A ribosome has one binding site for m-RNA and 3 binding sites for t-RNA. They are P-site (peptidylt-RNA-site), A-site (aminoacyl t-RNA-site) and E-site (exit site).
3. In Eukaryotes, a groove which is present between two subunits of ribosomes, protects the polypeptide chain from the action of cellular enzymes and also protects m-RNA from the action of nucleases.

Question 13.
Give examples of coordinated regulation or expression, of several sets of genes.
Answer:
Examples of coordinated regulation or expression of several sets of gene are:

1. If E.colt bacteria do not have lactose in the surrounding medium as a source of energy, then structural genes in Lac operon do not get transcribed and enzyme like β -galactosidase is not synthesized.
2. The development and differentiation of embryo into an adult organism.

Question 14.
Explain with example what is meant by positive control of gene regulation.
Answer:

1. A set of genes will be switched on when a substrate is to be metabolized.
2. This phenomenon is called induction and small molecule responsible for this, is known as inducer.
3. It is positive control of gene regulation.
4. For example, lactose acts as an inducer in Lac operon.

Question 15.
If operator gene is deleted due to mutation, how will E.coli metabolise lactose?
Answer:
If operator gene is deleted due to mutation, lac operon cannot be regulated. It will get transcribed continuously and enzymes required for lactose metabolism will get synthesized continuously.

Question 16.
Explain in brief the process of initiation during protein synthesis.
Answer:
Initiation of synthesis of polypeptide chain takes place as follows:

1. Small subunit of ribosome binds to the m-RNA at 5’ end.
2. Start codon is positioned properly at P-site.
3. Initiator t-RNA, (carrying methionine in eukaryotes or formyl methionine in prokaryotes) binds with initiation codon (AUG) of m-RNA by it’s anti-codon (UAC). Codon-anti-codon pairing involves formation of hydrogen bonds.
4. The large subunit and smaller subunit of ribosome bind in the presence of Mg⁺⁺.
5. Thus, initiator charged t-RNA occupies the P-site and A-site is vacant for next charged t-RNA.

Question 17.
What are the application of genomics?
Answer:
Applications of genomics are as follows:

1. Structural and functional genomics is used in the improvement of crop plant, human health and livestock.
2. The knowledge and understanding acquired by genomics research can be applied in medicine, biotechnology and social sciences.
3. It helps in the treatment of genetic disorders through gene therapy.
4. It helps in the development of transgenic crops having desirable characters.
5. Genetic markers have applications in forensic analysis.
6. Genomics can lead to introduction of new gene in microbes to produce enzymes, therapeutic proteins and biofuels.

Question 18.
Why is HGP important?
Answer:

1. HGP is associated with rapid development of Bioinformatics.
2. Knowledge gained about the functions of genes and proteins has a major impact in the fields like Medicine. Biotechnology and the Life sciences.
3. It has helped in identifying the genes that are associated with genetic characteristics.
4. The genetic basis of many hereditary diseases can be understood.
5. It has increased the understanding of gene structure and function in other species. As human beings have many of the genes same as those of flies, roundworms and mice, such studies will enhance understanding of human evolution.

Chart based / Table based Questions

Question 1.
Complete the following table:

Organism	Diploid chromosome number
Mouse	————-
Fruitfly	————
Roundworm	————-
Yeast	————–

Answer:

Organism	Diploid chromosome number
Mouse	40
Fruitfly	8
Roundworm	12
Yeast	32

Diagram Based Questions

Question 1.
a. Identify A and B in the following diagram.
b. Name the scientist who conducted this experiment.

Answer:
a. A : Smooth strain (III-S)
B : Rough Strain and Heat-killed Smooth Strain

b. F. Griffith conducted the experiment shown in the diagram.

Question 2.
a. Identify A and B in the given diagram.
b. What is the conclusion of the given experiment?

Answer:
a. A : Rough, nonvirulent R-strain B : Heat-killed virulent S-strain
b. When DNA of heat-killed S-strain bacteria is treated with DNase, mouse remains alive as transformation does not take place. This proves that DNA is the genetic material.

Question 3.
Identify A, B, C and name the scientists who carried out the experiment given in the diagram.

Answer:
Answer: A : Infection B : Blending C : Centrifugation Scientists who carried out experiment are Alfred Hershey and Martha Chase.

Question 4.
(1) Identify A, B and C.
(2) What are their sizes?

Answer:
(1) A : Circular, unfolded chromosome
b : Folded chromosome (40 to 50 loops)
c : Supercoiled, folded chromosome

(2) (A) 350 µ (B) 30 µ (C) 2 µ

Question 5.
Draw a labelled diagram of Nucleosome with H₁ histone.
Answer:

Question 6.
Identify A and B in the given diagram.

Answer:
A : Nucleosome
B : Linker DNA

Question 7.
(a) Identify A in the given diagram.
(b) What is the dimension denoted in ‘B’

Answer:
A : Solenoid B : 300 Å

Question 8.
Sketch and label process of formation of beads on strings/fibres from chain of nucleosomes.
Answer:

Question 9.
a. Identify A. Which enzyme joined them?
b. Identify B. What is its function ?

Answer:
a. A is Okazaki fragment. These fragments are joined by DNA ligase enzyme
b. B is RNA primer. It provides 3’ OH to which nucleotide gets attached by ester bond.

Question 10.
Draw a labelled diagram showing semi-conservative replication of DNA.
Answer:

Question 11.
Sketch and label, Meselson and Stahls experiment.
Answer:

Question 12.
Identify A, B and C in the following diagram.

Answer:
A : Transcription
B : Translation and
C : Reverse Transcription

Question 13.
a. Draw a labelled diagram of transcription unit.
b. What is the sequence of m-RNA and coding strand if sequence of template strand of DNA is

Answer:
a.
b.

Question 14.
a. The following diagram shows processing of ………….
b. What is capping?
c. Identify A, B and C.

Answer:
a. hnRNA
b. Capping is addition of methylated guanosine tri-phosphate at 5′ end of hnRNA.
c. A : Exon and B : Intron C : m-RNA

Question 15.
Draw a labelled diagram of t-RNA carrying Glutamic acid.
Answer:

Question 16.
Observe the diagrams (a), (b) and (c)

1. Which step of protein synthesis is shown in the following diagrams?
2. During initiation, which subunit of ribosome binds with m-RNA?
3. What are the three binding sites for t-RNA on ribosomes?
4. On which site of ribosome second and subsequent t-RNA arrives?
5. Which link is binding amino acids in diagram (b)?
6. Which chain is being released from ribosome in diagram (c) ?
   

Answer:

1. Translation
2. 30S or 40S
3. P site, A site and E site
4. A site
5. Peptide link
6. Polypeptide chain

Question 17.
Draw a labelled diagram – Working of lac operon.
Answer:

Question 18.
What is the process shown in the following diagram? Mention all the steps given in the diagram in a proper sequence.

Answer:
The process shown in the above diagram is DNA fingerprinting. The sequence of steps in the process are:

1. Isolation of DNA
2. Restriction digestion
3. Gel electrophoresis
4. Southern blotting
5. Selection of DNA probe
6. Hybridization
7. Photography,

Long Answer Questions

Question 1.
Describe Griffith’s transformation experiment.
OR
In the light of Griffith’s experiment, explain the action of two strains of streptococcus pneumoniae and give his conclusion.
Answer:

(1) In 1928, Frederick Griffith, carried out experiments with bacterium Streptococcus pneumoniae (which causes pneumonia in humans and other mammals).

(2) Griffith used two strains of Streptococcus pneumonia:

• S-type (Virulent, smooth, pathogenic and encapsulated).
• R-type (Non-virulent, rough, non- pathogenic and non-capsulated).

(3) Experiments carried out by E Griffith:

• Mice were injected with R-strain bacteria and they survived (no pneumonia).
• Mice injected with S-strain bacteria developed pneumonia and died.
• When heat-killed S-strain bacteria were injected in mice, the mice survived.
• On injecting a mixture of heat-killed S-bacteria and live R bacteria, the mice died.

(4) Griffith obtained live S-strain bacteria from the blood of the dead mice.

(5) He concluded that the live R-strain bacteria must have picked up something (which he called transforming principle) from the heat killed S bacterium, and got changed into S-type. Transforming principle allowed R-type to synthesize capsule and it became virulent.

(6) Thus, F. Griffith first demonstrated genetic transformations.

Question 2.
Describe Avery, McCarty and MacLeod’s experiments.
Answer:

• In 1944, Oswald T. Avery, Colin M. MacLeod and Maclyn McCarty proved that the DNA is a genetic material (transforming principle).
• They purified DNA, RNA, proteins (enzymes) and other materials from heat killed S-strain cells and mixed them with cells of R-strain bacteria separately to confirm which one could transform living R cells into S cells.
• Only DNA was able to transform harmless R-strain into virulent S-strain.
• They also demonstrated that proteases, RNases did not affect transformation. Thus it was proved that the transforming substance was neither a protein nor-RNA.
• When DNA was digested with DNase, there was no transformation.
• These experiments proved that the transformation of Live R-strain bacteria into S-strain type was because of DNA of bacteria of S-strain.
• Thus, they proved that the DNA is transforming principle.

Question 3.
Explain how Hershey – Chase experimentally proved that DNA is the genetic material.
Answer:

(1) Hershey and Chase worked with bacteriophages (viruses that infect bacteria and which are composed of DNA and protein coat).

(2) They cultured E. coli bacteria in medium containing radioactive phosphorus 32p. By infecting these bacteria with bacteriophages, Hershey and Chase could develop bacteriophages having DNA labelled with 32p. as DNA contains phosphorus and proteins do not.

(3) They also cultured E. coli bacteria in medium containing radioactive sulphur 35s. By infecting these bacteria with bacteriophages, they developed
bacteriophages whose protein coat was labelled with 35s, as proteins contain sulphur and DNA does not.
[Note : Viruses cannot be cultivated in medium.]

(4) Experiment involved three steps.

• Infection : Both the types of radioactive phages were allowed to infect E.coli bacteria grown on the medium containing normal ‘P‘ and ‘S’.
• Blending : Then bacterial cultures were agitated in blender to break contact between bacteria and parts of viruses that did not enter bacterial cells.
• Centrifugation : It was done to separate bacterial cells as a pellet. Parts of viruses which did not enter bacteria remained in the suspension.

(5) Observation:

• Radioactive ‘S’ remained in suspension.
• Only radioactive ‘P’ was found inside the bacterial cell in the pellet.

(6) Thus it was proved that DNA is the genetic material which enters bacterial cell and not protein.

Question 4.
Explain the formation of beads on string, solenoid fibre, chromatin fibre and chromosome.
Answer:

• Beads on string (11 nm in diameter) : Under an electron microscope, nucleosomes in thread like chromatin look like ’beads-on- string’.
• Solenoid fibre (30 nm in diameter) : Six such nucleosomes get coiled and then form solenoid that looks like coiled telephone wire.
• Chromatin fibre (200 nm in diameter) : Further supercoiling tends to form a looped structure called chromatin fibre.
• Chromosome (1400 nm in diameter) : Chromatin fibre further coils and condenses at metaphase stage to form the chromosomes. Each chromatid is 700 nm in diameter.
• Non-Histone Chromosomal Proteins (NHC) are the additional sets of proteins that contribute to the packaging of chromatin at a higher level.

Question 5.
Explain the components of a transcription unit with the help of a diagram?
Answer:

Transcription unit (Each transcribed segment of DNA) consists of the promoter, the structural gene and the terminator.
(1) The promoter:

• The promoter is located towards 5′ end of structural gene, i.e. upstream.
• It is a DNA sequence that provides binding site for enzyme RNA polymerase.
• In prokaryotes, sigma factor sub unit of the enzyme recognizes the promoter.

(2) Structural genes:

• Template strand (Antisense strand) : DNA strand having 3’→ 5’ polarity acts as template strand as DNA dependent- RNA polymerase catalyses polymerization in 5’ → 3’ direction.
• Sense strand : The other strand of DNA having 5’ → 3’ polarity is complementary to template strand. It is called as sense strand. The sequence of bases in this strand, is same as in RNA (where Thymine is replaced by Uracil). It is the actual coding strand.

(3) The terminator:

• The terminator is located at 3’ end of coding strand, i.e. downstream.
• It defines the end of the transcription process.

Question 6.
What have we learnt from the Human Genome Project?
Answer:
We have learnt following salient features of human genome from the Human Genome Project.

1. The human genome contains 3164.7 million nucleotide bases.
2. The average gene consists of 3000 bases.
3. Largest known human gene is dystrophin at 2.4 million bases.
4. Total number of genes is estimated to be 3000.
5. 99.9% nucleotide bases are exactly the same in all people.
6. The function of about 50% of the discovered genes are unknown.
7. Less than 2% of the genome codes for proteins.
8. Repeated sequences make up a very large portion of the human genome. They can shed light on chromosome structure, dynamics and evolution.
9. Chromosome 1 has most genes (2968) and the Y has the fewest (231).
10. Single nucleotide polymorphism have been identified at about 1.4 million locations. It is useful in finding chromosomal locations for disease-associated sequences and tracing human history.

Question 7.
Describe the steps involved in DNA fingerprinting ?
Answer:

Steps involved in DNA fingerprinting are as follows:
1. Isolation of DNA : The DNA can be isolated even from the small amount of tissue like blood, hair roots, skin, etc.

2. Restriction digestion:

• The isolated DNA is treated with restriction enzymes which cut the DNA at specific sites to form small fragments of variable lengths.
• Variations in the lengths of restriction fragments are known as Restriction Fragment Length Polymorphism (RFLP).

3. Gel electrophoresis:

• The DNA samples are loaded on agarose gel and electrophoresis is carried out.
• Negatively charged DNA fragments move to the positive pole.
• Separation of fragments depends on their length and it results in formation of bands.
• dsDNA is then denatured into ssDNA by alkali treatment.

4. Southern blotting : The separated DNA fragments are transferred to a nylon membrane or a nitrocellulose membrane.

5. Selection of DNA probe:

• DNA Probe is a known sequence of single- stranded DNA.
• It is obtained from organisms or prepared by cDNA preparation method.
• The DNA probe is labelled with radioactive isotopes.

6. Hybridization:

• In this process, probe is added to the nitrocellulose membrane containing DNA fragments.
• The single-stranded DNA probe pairs with the complementary base sequence of the DNA strand.
• As a result DNA-DNA hybrids are formed on the nitrocellulose membrane. Unbound single-stranded DNA probe fragments are washed off.

7. Photography : The nitrocellulose membrane is then kept in contact with X-ray film. DNA bands, due to radioactive probe, give photographic image on X-ray film. This is autoradiography.